It's very difficult to make an intelligent and informed choice when purchasing a smartphone or tablet, especially if you've never owned one before.  The following is a list of features to look for, each with a discussion of why they're important.

Tablets and smartphones are both "portable devices" and operate similarly using the same operating systems and apps, with two distinctions:  First, anything with a 6" screen or smaller is a smartphone, while anything with a 7" screen or larger is a tablet.  The more puzzling distinction, though, is that you cannot use a tablet as a phone.  It may or may not have 3G or 4G/LTE data service, which means it's getting data via a cellphone service, and it has speakers and a microphone, but it cannot be used as a phone.

OPERATING SYSTEM:  Arguably the most important decision, as it forever locks in your selection of apps.  In general, there are four popular operating systems:  Apple, Android, Kindle, and Windows.

Android is an "open-source" operating system, meaning that although Google maintains the license and the database, it's free for anyone to use, and anyone can write apps for use with it.  This leads to a bit of "wild west" in the market for apps, with an overwhelming array of titles to choose from.  Some apps are free, some cost a few bucks -- often after a free trial period -- and some are supported by advertisements.  It can be startling to see an advertisement come up on your phone.  Many of the advertiser-supported ones offer an option that you can pay a few bucks to make the ads go away.  Even when you pay for your apps, you'll find them far more reasonably-priced than software for your PC ever was.

The other three operating systems are proprietary, meaning you have to deal with the organizations involved for apps.  The implications vary.

Apple is immensely popular, and the public can submit apps, but all apps must be tested and approved by Apple.  This is what many people like about Apple; you're not likely to get buggy or virus-infested apps from them.  Still, many Apple device owners speak of "jailbreaking" their phones so they can load non-Apple-approved apps.

Kindle uses a "forked" version of Android.  To be clear:  IT IS NOT ANDROID.  Because Android is open-source, Kindle freely copied its structure and modified it for its own use.  And that modification means you cannot load Android apps; you must get your apps from Kindle.  Kindle sells its tablets at a loss and then charges enough for its apps to make up for it.  Do you think this is an acceptable business plan?

Windows is a whole 'nuther idea in operating systems:  Rather than creating a clean sheet operating system designed from the ground up for portable devices, MicroSoft devised its tablets and its operating system to interact and coexist with its PC operating system.  Many commercial users find this ideal.  First off, they don't need to retrain their employees on a new system, and second their files can be opened and worked with on either type device.  MicroSoft promotes its tablets as being capable of doing real work.  All of this is valuable, but note that these benefits will diminish with time as Android and Apple systems develop further and apps are introduced that facilitate translations from PC's to portable devices.

OPERATING SYSTEM UPDATES:  The apps you install will update automatically, but the operating system may not -- at least, not with an Android device.  Usually, the Android version your device comes with is the one you'll be stuck with until you buy a newer device.  The only way to update to a later release is if the device manufacturer issues an update.  At least one manufacturer claims that every time a new release of Android comes out, they will publish an update so owners of their products can always be using the latest operating system.  Shame on all the manufacturers who are not making this promise.

CAMERA:  All of these devices have cameras these days; most of them have two, one facing the user and a better one facing away from the user.  While most features on a portable device are either-you-have-it-or-you-don't, the camera is where you really need to be concerned about the quality of the feature.  Allow me to illustrate the importance:  In five or ten years, you'll probably move on to a new smartphone, but you'll probably want to keep some of the pictures you've taken with it forever.  Pictures of people who have since died, places you'll never go again, the hair you once had -- these memories are likely to be of great importance to you someday.  If you've taken all those photos with a lousy camera, you'll regret it for the rest of your life.  You could carry around a good digital camera separate from your phone, but nobody actually does.  When something happens, especially something unexpected, it's your smartphone you're going to whip out to capture it for posterity.  You want the best camera you can get, period.

The first indication of quality in a camera is the number of megapixels.  Your HDTV is 1920x1080 resolution, meaning 2,073,600 pixels or 2 megapixels.  Any decent smartphone camera will be 5 megapixels or more.  Sometimes when you take a picture, what you really wanted was just in the center of the image, so you crop away 3/4 of the image -- and your 5 megapixel image just became a 1.25 megapixel image.  You can't have too many megapixels, but remember that more megapixels means the photo takes up more data storage space.  You can reduce the resolution later to reduce the data storage requirements, although most find it easier and better to just buy more data storage space!  It seems to get cheaper every day.

Note:  The default resolution that the camera uses may not be its maximum resolution.  Often, the maximum resolution may be a nearly square image while the default is an image the same shape as the smartphone's screen.  That means that the default is cropping off part of the image to fit your smartphone screen.  You might as well change the default to take the entire image; you can crop it later if you wish.

There are other things to look for in the camera, though.  One is a flash.  This author has a Moto e 4G/LTE smartphone that does not have a flash.  Not only can you not take pix in the dark, you also don't have the "flashlight" app that holds the flash continuously on to help you find your way around.  The only thing it can do is turn on the screen bright white, which isn't nearly as good.  Most devices seem to have a flash for the camera looking away from the user but not one facing the user.

There's also zoom.  A mechanical zoom would be great, but apparently they don't fit in the narrow thickness of a tablet.  One company compensates by offering a 41 megapixel camera (!) which means you can crop 90% of the photo away and still have a 4 megapixel image.  Theoretically at least, this is the same thing as a 4 megapixel camera with a 3X zoom.  And, to be clear, this is exactly the same thing a digital zoom does; it just crops part of the image before you even take the picture.  You can also buy, for a few bucks, a little 2X telephoto lens that you can stick over your device lens, held either by magnet or by a big spring clip; these work OK but they're not convenient to carry around with you, and they're not convenient to get out of your pocket and affix to your device while an airplane is crashing or whatever.

There's even focus.  Most of these cameras don't even have any sort of mechanical focus.  Apple has reportedly come out with one with a real mechanical focus using a nearly microscopic motor.  Hopefully others will follow suit.

When shopping for a device, nothing beats just taking some pictures and seeing how they come out.  You can usually do this in the store.  Don't just look at the screen, though; they'll always look good that way.  Rather, find the zoom function and zoom in on the picture you just took and see how the details look when blown up to fill the screen.  Take pix of something close up, and take pics of things moving (like ceiling fan blades), as these present specific challenges to cameras.

These cameras can also be used to record video, again with varying levels of quality.  A good baseline would be HDTV quality, which is 2 megapixels recording at 60 frames per second.  That's hard, though; it takes premium processing power to get that many frames per second, so some compromise at half that, 30 frames per second.  You'd be hard-pressed to tell the difference, since the human eye only sees about 16 frames per second.  Still, if you try to play that video back in slow motion, the lower frame rate will become apparent.  Better systems should be able to record video at the new 4K resolution, which is 8 megapixels.  All of this will make your videos look really good on America's Funniest -- or when you're showing them to your grandchildren 40 years from now.

GPS:  GPS stands for Global Positioning System.  It's a system of satellites in low Earth orbit with atomic clocks on board that emit signals that can be picked up by a handheld device and used to determine your location to an accuracy of roughly 30 feet.  Good enough for targeting missiles and bombs, which is what it was originally intended for.  Since inception it's been supplemented with WAAS, an on-the-ground local correction, which improves the accuracy to about 10 feet depending how close you are to the WAAS station.  Good enough for landing airplanes.  The next generation of satellites is already planned, and accuracy will be within millimeters, good enough for tracking plate tectonics.

Many people believe a "GPS" is a device that sits on the dashboard of your car and
presents a map and has a voice that tells you when to turn.  That's a navigation system and it's one application of a GPS, but not the only one.  Some GPS devices have no maps at all and merely provide an arrow and a distance to a set destination; you have to figure out for yourself how to get there.  This latter type is more appropriate in the woods than on the highway.

If you buy a smartphone in the US, it has GPS.  It's required by law so that a 911 operator can pinpoint your location in the event of an emergency.  You can turn off the "location services" so your apps don't have access to the GPS, which some people do because they're convinced that Big Brother is tracking them, but you cannot turn off the GPS itself; if you call 911 with that smartphone, the operator will know where you are.

The same is not true for a tablet.  Since a tablet cannot be used as a phone, whether or not it has a GPS is optional, and if it has GPS you can turn it off to save battery life.  Many Kindles do not have GPS; they try to fake it using the location data of wi-fi servers in the vicinity.  This works OK in the big city but not so well in the woods where you really need it.

As long as your device has GPS, you don't need to buy that navigation system for your car.  Your smartphone or tablet will do the job, including providing voice commands.  Just download the appropriate app and set the device on the dashboard.  You can also download maps for it and update them as required, often for free.  There are even versions that will operate as a "heads-up display": set the tablet on top of the dashboard and look at the reflection of the display in the windshield as you drive.

You don't need a speedometer either, actually.  Your device can tell you how fast you're going, and more accurately than the speedometer in your car.

MEMORY CARD PORT:  The Android operating system takes about 3-4 GB of data storage space on your device.  If the device came with 8GB built in, you have 4-5GB of available space to store your stuff.  If it came with 16GB, you have 12-13GB of space to play with.

That internal data storage space is a good place to store your apps.  It is not a good place to store your photos or other items of personal importance to you.  If your device gets smashed or stolen, it's gone.  Buy a new device and you can just install all your apps again in a matter of minutes, but you'll never get those photos back.

A better idea is to buy a 16GB microSD memory card and plug it into a memory card port on your device.  It won't help if it's stolen, but it will help if it's broken; you can just unplug the memory card from a broken device and plug it into a new device and you're good to go.  Within the Settings menu you can find options to select what gets stored in the internal memory and what goes on the card; if the internal memory gets full, just move some stuff to the card.  That memory card port actually gives you infinite data space; if you ever fill up that 16GB card you can just buy more 16GB cards and swap them in and out.  A microSD card is about the size of your pinky fingernail, so the toughest thing about swapping them in and out is not losing them in the couch cushions.

MicroSD card

Note:  MicroSD cards are available up to at least 256GB.  However, your device may not be able to make use of that much capacity.  Check the specs on your device; if it says something like "16GB expandable to 32GB", it's trying to tell you that anything larger than a 16GB memory card won't work in it.

The other idea is to use "the cloud", basically using an online storage provider as your personal storage space.  Snap a pic and it automagically uploads to this site, and you can retrieve it to look at it just as easily.  Even if your device gets stolen, your photos are safe. 
Online presents its own issues, though; make very sure to use a password that nobody would guess in a million years if you don't want your bank account information to end up in the hands of the Chinese.  Note:  If you're having to pay by the byte for your data plan, you definitely do not want to use cloud storage as it will run up data charges moving your files in both directions.

Key point:  Some smartphones and tablets don't have a memory card port!  Google's own Nexus tablets don't, for example, because they expect you to utilize their cloud.  For me, the lack of a memory card port is a deal breaker, but you can decide for yourself.

Anything really important you should be backing up anyway, either to some storage device at home or someplace online.  For just a couple of bucks you can buy a USB OTG cable (see below) or adapter that plugs into your device's charging/data port and enables you to plug in a USB thumb drive or any of several other types of data storage systems, so backing up your important stuff shouldn't be difficult.  Just remember to do it every now and then.

DATA/CHARGING PORT:  Smartphones have a small data/charging port that's actually a standard, you can buy cords to fit it anywhere.  Large tablets go a different route, though, and have a broad, flat plug.  The reason is that the standard plug is rated to handle only 0.5 amps charging current, but large tablets will draw 2.1 amps.  Apple tablets use one of these broad connectors, and their products are common enough you can buy suitable cords in Walmart.  Samsung Galaxy tablets use a broad plug that looks exactly like the Apple connector, but it's not; neither one can be used with the other manufacturer's device.  If you have a Samsung tablet, don't just buy a cord with a connector that looks right; make sure it's actually intended for a Samsung rather than an Apple.

CHARGER:  All of these devices charge at 5VDC because that's the standard power supply in a USB port.  Smartphones typically charge at 0.5 amps, and such chargers have become ubiquitous -- you can buy one from a bin in the checkout line at the Dollar store.  Some smartphones don't even come with a charger to save money, presuming you already have one!  Remember, though, that you probably want two -- one that plugs into a wall outlet in your house and one that plugs into the cigarette lighter in your car.  You may also need a suitable cable to connect the charger to the smartphone; such cables are also easy to find in a Dollar store.

If you have a tablet, things get trickier.  A tablet draws more current -- 2.1 amps seems pretty standard -- which is more than the cheapo Dollar store chargers can provide.  Worse, though, is the fact that a couple of those cheap chargers have caught fire or melted down when overloaded and damaged somebody's car or something, and the tablet company got sued for it!  So now both a Samsung and an Apple tablet will detect whether your charger is up to the task, and if not they will only draw 0.5 amps from them.  That big screen alone draws more than 0.5 amps, so if the tablet is powered up it will gradually be draining the battery even though it's plugged in.  The tiny battery symbol in the corner on the screen on a Samsung tablet will have a red X in it to indicate the charger isn't keeping up.  If the tablet is turned off it will charge the battery eventually, it'll just take a long time to do it.  What you really want is a charger rated at 2.1 amps.  They're not too difficult to find, but note that some of them still don't really charge too well.  You want to look for a quality product there.

USB PORT:  The USB connector is a really handy standard, allowing one to connect your keyboard, mouse, printer, whatnot to your PC all with the same connector.  Then Apple and Android portable devices appeared without such ports!  Almost inexcusable, but it's probably because they wanted the devices to be thin and the standard USB port is too thick and bulky.  You can buy a jumper that you can plug into your data/charging port that will allow you to plug in a USB device or thumb drive.  It's called a "USB OTG cable", OTG standing for "on the go".

USB OTG cable

You'll also have to download an app to make it usable, as the device probably doesn't come with the capability of recognizing USB devices.  MicroSoft, meanwhile, does include USB ports in their Windows tablets -- a valuable selling point.

WI-FI:  Wi-Fi is a standard for short-range wireless communication, typically good for 100 feet or so.  It can be used to connect computers within an office, or to connect a computer to a printer in the next room.  It can be used to connect portable devices to one another, including transferring files from an Apple device to an Android device when there are no cords that could connect the two.

When most people use the term "wi-fi", though, they're referring to one particular application of this wireless standard:  The use of a "router" hard-wired into the internet to provide wireless internet connectivity to devices within range.  You can walk into your local Burger King, grocery store, or library and there's a good chance they provide free wi-fi service, just log in and agree to their terms.  Wi-fi is so common you can typically just drive down the street and several will appear on your device as being within range.  It is very, very easy to find free wi-fi service in most urban areas.  What's more, nobody bothers to turn their wi-fi off when they close for the evening, so you can often park outside a business at 3 in the morning and make use of their wi-fi.

Many wi-fi systems are password protected, though; you can't connect to them without knowing the password.  It'll tell you when you look at the list of wi-fi's within range which ones are secured.  If you are the owner of the router, you may choose to password protect it to prevent strangers from using it and running up your data bill or from simply tying up the system so it runs slower for you.  Many people have internet service that doesn't keep track of how much data is used, so they'll just leave the wi-fi open deliberately so anyone within range can use it.  Finally, there are organizations that offer wi-fi connectivity for a fee; you'll see that when you try to log on, and if you're not interested you can tell your device to forget those.

There are actually two standards for wi-fi:  IEEE 802.11(a) and 802.11(b/g).  These operate on different frequencies.  Most routers provide both, and when you connect your device will connect to whichever at random, or sometimes both.  This author owns a Moto e 4G/LTE that has only 802.11(a) capability.  Normally one wouldn't notice, but I happened to be in a Hardee's where everyone else was using the wi-fi with no problem but I couldn't connect.  It turned out the 802.11(a) portion of their router was malfunctioning, and I was the first customer who noticed.

Beware of "spoof" wi-fi providers.  A wi-fi connection in itself is secure, nobody can hack into the communication between you and the wi-fi router.  But crooks get around that by providing their own wi-fi router and making it look like something trustworthy.  Like, they'll give it the name of a motel nearby so you think you're connecting to the motel's wi-fi.  But when you connect, they can monitor everything you do.  If you log into your bank account using your password, they now know your bank account number and your password.  Not good.  They can even wander around in the files on your device, so it's good to have the really important ones password protected.

CELLULAR DATA:  When you sign up for a cell phone service, your contract will usually include terms for talk, text, and data.  Data is what you need to use the internet.  You can get data either via your cell phone service or via wi-fi, but the wi-fi is only usable within 100 feet or so of a wi-fi router whereas the cellular data is usable anywhere with cell phone service.  Wi-fi is often free while cellular data usually has costs associated with it, so your device may be capable of automatically choosing to use wi-fi when it's available.

Obviously, all smartphones will have cellular capability, and hence can utilize a cellular data plan.  Tablets might not have cellular data capability at all, however; in fact, it's sometimes a rather expensive option.  It's possible to buy a device to add cellular data capability to your tablet; the "hotspot" discussed below is one such option.

The speed of the cellular data capability is indicated by the "generation":  2G, 3G, or 4G/LTE.  2G is basically dial-up speed, it's painfully slow but better than nothing.  3G is an order of magnitude faster than 2G, and 4G/LTE is an order of magnitude faster than 3G.  It's called 4G/LTE because it really doesn't meet the requirements originally set out as being "4G", but nothing does yet, LTE is the best we've got.  In this day and age, there's no excuse for buying a smartphone that doesn't have 4G/LTE capability.

HOTSPOT:  A hotspot is wi-fi turned around, where your device becomes the source of the internet connectivity rather than the user.  Your device is connected via its cellular data connection, and then makes that data available via wi-fi so that other devices can log on.  This is really slick, and can provide wi-fi service in a moving car or waaay out in the woods.  Some cars now come with a hotspot built in at the factory, and spend millions of dollars in advertising proudly telling you you're buying a car with a feature you already have in your shirt pocket.  Of course, you have to pay for the cellular data service.  You probably want a secure password on your hotspot so strangers cannot use your data.

The original idea for hotspots was a specialized device, something you set up in your home or car and permanently wire in.  But it was quickly realized that a smartphone could do the job since it has wi-fi and cellular data capabilities.  On early smartphones you'd download a hotspot app, but on later models the feature comes built-in.

I'm pretty sure that any smartphone can be used as a hotspot.  The data plan is another story.  Many cellular service providers want to make money providing hotspots and deliberately prevent you from using your smartphone as a hotspot; when you try to turn the hotspot on, it goes through a verification step to check if your cellular provider permits that, and if it doesn't you're outta luck.  You either have to pay extra, or worse you may have to purchase a separate device.  If you intend to use your smartphone to provide a hotspot, make very sure your service provider permits this before signing up.  As an example, as of this writing SmartTalk Wireless does not permit their data to be used to run a hotspot, while Verizon Prepaid does.  This is interesting, as both operate on the same network, Verizon's.  SmartTalk charges the same monthly fee but provides 5GB of data rather than 2GB, and slows down when you exceed that limit rather than shuts it off altogether as Verizon does.  All that sounds like SmartTalk is a much better deal -- until you realize that to use SmartTalk as a hotspot you'll need to pay another monthly fee, whereas you can just go ahead and use the Verizon Prepaid service for a hotspot.

This author uses his Moto e 4G/LTE as a hotspot, and it's worth noting that the range of that wi-fi hotspot is considerably less than that of a typical wi-fi router -- only perhaps 15-20 feet.  Since the hotspot is a cell phone, that's not really an issue; just move the phone closer to the computer or whatever that you're connecting to the hotspot.  If, however, you intend to provide internet connectivity all over a house so that everyone can log in in their bedrooms, be aware that a single smartphone hotspot probably won't work very well.  You'll either need multiple smartphones or a different scheme.

Note:  When a call comes in, the hotspot shuts off as soon as it starts ringing.  Whatever is happening on your wi-fi comes to a stop, and you'll start getting connection errors if you try to open new pages or download files.  As soon as the phone call is disconnected, the hotspot resumes operation.

By the way, when using your smartphone as a hotspot, it doesn't have to be wi-fi.  It can also provide internet connectivity via Bluetooth (see below) or by being connected to your computer via a USB cable.

BLUETOOTH:  Bluetooth is another standard for short-range wireless communication, even shorter range than wi-fi:  around 20 feet or less.  Its intention was to eliminate the need for wires connecting your keyboard, mouse, and headphones to your computer.  Since bluetooth accessories are typically battery powered, the standard is deliberately designed to maximize battery life.  The batteries in the accessories will typically last a year or more.

If you own a laptop computer, you know there are ports and sockets all over the thing for plugging in various accessories.  Smartphones and tablets are the opposite; they may have only one data/charging port and one headphone connection.  Anything else you wish to connect will probably need to be either a wi-fi device or a bluetooth device.  This author has a bluetooth keyboard and a bluetooth mouse that work wonderfully with his smartphone and tablet.  The only trick is convincing the device to not bring up that onscreen keyboard when using the bluetooth keyboard; there's an app for that.  And it should be noted that the mouse is faking some of its functions, since an Android device doesn't even have some of the same functions that were on the PC that the mouse was intended for.

Bluetooth accessories tend to be rather tricky to set up.  The instructions often involve something that sounds nutty, like pressing and holding all three buttons on the mouse at the same time.  Once set up, though, you never need to fiddle with it again; your device and your accessory will remember each other.  You should change the name on the accessory to something personal like "Joe's mouse" just in case you're ever in a room where others are using similar accessories; don't just use the default name. 

Note that there are a lot of "wireless" mice on the market that are not Bluetooth.  They use a "dongle", a tiny receiver that plugs into a USB port on your computer and communicates wirelessly with the mouse.  Those won't work on a smartphone or tablet because there's no USB port to plug the dongle into.  You need to find true Bluetooth accessories.

Bluetooth can also be used to connect one handheld device to another, to transfer files back and forth or the like.

MOTION SENSORS:  Smartphones and tablets have motion sensors built in so they can tell when you're moving them.  Those same sensors have long been used in video game controllers.  When they first hit the market, it was surprising just how accurate they are, and it still can be amazing to watch them work.  The sensors in your smartphone, for example, are so accurate that you can install an app, set the phone on the passenger's seat in your car, and then floor the gas pedal and it'll tell you how many horsepower your engine has by sensing its acceleration!  There's even an app called MyShake that uses people's smartphones the world over to help track earthquakes.

MAGNETIC FIELD SENSOR:  Better portable devices have a built-in magnetic field sensor.  You can download a compass app that turns your device into a compass.  That sounds simple until you try it; it's a really amazing compass, much better than that plastic thing you had in your Boy Scout days.

Note, however, that many of the cases you can buy to protect your smartphone or tablet come with magnets built in to hold the case closed!  Those magnets render the built-in magnetic field sensor useless.  You'll need to either take the device out of the case or cut the magnets out to use the magnetic field sensor features.

There are also telephoto lenses for use with the camera that attach to the device with a magnet.  There may be nothing on the device for a magnet to stick to, but the lens comes with a little peel-and-stick metal ring to attach permanently around the camera on the device so you can stick the lens on when you need it.  The metal ring isn't a problem for the magnetic field sensor, but the lens itself certainly is.  You'll have to leave that lens in the car or otherwise a good ways away if you want your magnetic field sensor to work properly.

This author's Moto e 4G/LTE does not have a magnetic field sensor.  If you try to load a compass app, it tells you right away that the app won't work on this device.  There are compass apps that will fake it using the GPS sensors; when you move, the GPS knows which way you moved, and the app tells you which way is north accordingly.  It's far less accurate or useful than the real compass app, though.

MICROPHONE:  A microphone is cheap, so all devices should have one.  It looks like a pin hole in the case.  Be sure not to cover it with a screen protector or whatnot.  There might be two microphones, one on the front and one on the back, with the one on the back side used for recording video with sound.

SPEAKERS:  A smartphone has a speaker that you put up against your ear when talking, and it can work loudly enough to put your phone in speakerphone mode.  Tablets often have two speakers for stereo sound.  If you listen on headphones or earbuds, though, I believe you'll get stereo from any device.

INFRARED EMITTER:  The author's Samsung Galaxy Note 10 has an infrared emitter.  This enables the tablet to be used as a remote control for a TV, DVR, etc.  Of course, you don't need another remote, but what this thing can do goes far beyond that.  You can program it to turn the TV on and off, change channels, record programs on the DVR, whatever, all while you're not there.  Just leave the tablet on and laying on the table with the infrared emitter pointing towards the TV.  And if the internet is available, the tablet can search online listings for shows you want to see and record them for you.  Yet another feature you never knew you needed!

STYLUS:  The difference between a Samsung Galaxy Tab and a Samsung Galaxy Note is that the Note comes with a stylus, a pen-looking thing that stores away in a little slot in the tablet.  It's got a really weird point on it that the screen can sense without even touching it!  It only needs to be within a millimeter or so.  It supposedly can be used for all sorts of features, including detailed drawing and writing (far less clumsy than trying to draw or write with your finger).

Note that you can buy a "stylus" for use with a smartphone or tablet in any Dollar store, sometimes with a pen on the other end.  These are not the same thing; they are merely a simulated finger, a little black rubber dome on the tip that conducts electricity as well as a fingertip so the screen can detect its touch.  It helps a little, but it doesn't even keep fingerprints off the screen; the little black rubber dome leaves marks, too!  The stylus that comes with the Samsung Galaxy Note is completely different and provides a much more accurate pointing capability.

NFC CHIP:  NFC stands for "Near Field Communication", and it's yet another short-range wireless communication standard -- this one is really short range, on the order of a few inches!  It's this function that enables you to transfer pictures from one smartphone to another by basically bumping them together.

REPLACEABLE BATTERY:  Back in the day, anything that used batteries could have the batteries replaced -- even things that used rechargeable NiCad batteries since they were forever going bad.  With modern lithium batteries, however, many devices come with the battery built in and inaccessable.  This is an indication of how reliable lithium batteries are.  Still, being able to replace the battery is a good thing just so you can have two or more batteries and swap them out when one needs charging.  If your battery is inaccessable, it's still possible to work with a dying smartphone by carrying a spare battery pack that plugs into the phone's data/charging port.  It's just not as convenient as swapping out batteries.

WIRELESS CHARGER:  Because it's just too tedious to have to plug your device into its charger, you can now get devices that you merely set on top of a charger and the battery is charged via induction.  Probably wastes energy, perhaps a nickel's worth of electricity a year.  Some owners have found the induction coil wrapped around the battery and concluded it was an antenna that the NSA was using to spy on them, which led to all sorts of idiotic conspiracy theories on Facebook.

THUMBPRINT SENSOR:  Supposedly the ultimate in security, some devices now have a thumbprint scanner.  Do you really need it?  Perhaps not, but it might be easier and quicker to press your thumb against the scanner than to type in a lengthy and secure password when opening up your phone.

One other thing to remember:  If you're relying on passwords for security, you have to be careful where you're standing when you type in that password.  Closed-circuit video cameras are everywhere these days, and you never know who's on the other end watching you.  They can just jot down your password for later after they steal you phone.  With a thumbprint sensor, you don't care who's watching.

PAYMENTS:  Apple Pay and Google Pay are schemes by which you can use your device as a credit card.  Just wave it near the credit card reader at a checkout and it magically makes a payment for you.  As of this writing this is just getting off the ground here in the US, but it's certain to catch on; one less thing to carry.  Many people in Africa already rely upon smartphones for all their banking and money transfer needs.

WATERPROOF:  There are only a couple of handheld devices that even claim to be waterproof, and of course they're making the most of it in their advertisements.  As well they should; the notion that any such devices were ever made that were not waterproof is shameful.  One's smartphone becomes part of one's life, you carry it around whereever you go and whatever you do.  It needs to be durable and sturdy, and that includes being waterproof.  Many of us put cases around our devices to help protect them, but that usually won't help if you drop them into the swimming pool.

If you know there's a risk of your device getting wet, the thing to do is put it in a baggie -- a tough, reliable freezer bag type.

ROUNDED EDGE:  The Samsung Edge comes with a glass screen that curls around the edge of the device.  Perhaps the single most pointless feature ever conceived.  Not cheap, either.  What you really want in a handheld device is a raised bezel around the glass screen so that you can set it face down on a flat surface without scratching the glass.  That won't help when setting it on nonflat surfaces, but there are so many flat surfaces in this world that such a bezel will dramatically reduce the amount of damage your screen suffers.

HANDLE:  One really nice feature on a smartphone or tablet is a convenient handle or grip to hold it by.  Aren't those wonderful?  Can't answer that, because none of them have one!  Smartphones typically have a touch-sensitive screen all over the front and buttons down one or both sides so it's simply not possible to hold the %$^&^% thing without buttdialing somebody!  Tablets are even worse, having the same touchscreen and buttons but too large to easily grip between your thumb and fingers.  Hopefully, somebody will figure this out soon and start designing handheld devices to be handheld.