Here is some general information about Android, with some tips and hints that I have discovered.
 

Operating System

The operating system on your tablet or phone could be Android, but there are different versions just like there are different versions of Windows on PCs. The code name for the versions of Android has had a confectionery theme, with each new one in alphabetical order. They are Cupcake (1.5), Doughnut (1.6), Eclair (2.0-2.1), Froyo (2.2-2.2.3), Gingerbread (2.3-2.3.7), Honeycomb (3.0-3.2.6), Ice Cream Sandwich (4.0-4.0.4), Jelly Bean (4.1-4.3), KitKat (4.4-4.4.3) and Lollipop (5.0). The higher the number, the more up to date the operating system is, but unlike PCs, you cannot update your device to the latest version unless the manufacturer of your device issues the relevant update. Older devices (either tablets or phones) may never get an update, as the manufacturer may have a newer phone with a more recent version of Android and won't bother to issue an upgrade. And yes, upgrading your device will wipe all your data unless you have backed it up beforehand.

Google Account

This takes us on to your Google account. As Google created the operating system, it can be used to back up your apps and data, so if you change your device, all you have to do is enter the same Google account and your apps and data will be restored. But it will not back everything up. The position you are in a game is unlikely to be backed to your account, and neither are the preferences you have in other programs. There are programs that can back up everything, but they need access to system files that the default programs don't have access to. In order for them to work your tablet/phone may need to be rooted, which means installing a copy of the operating system with access to the root files, hence it is called rooting your device. You can use your Google account with multiple devices and the data that is backed up will be synced automatically on each device, so emails, contacts and your calendar will be the same on all the devices and a change on one device will be shown on the other.

Play Store

Your account also allows you to access the Google Play Store, where you install your apps from. The apps have to be checked before they appear on the Play Store, so installing from here is quite safe. You can change the settings on your device to allow you to install programs from other sources. An installation file for an app has an apk file extension, so you can copy these files and run them on an Android device to install them. This is where problems may occur as the author of the app might have only written it for a phone or a particular screen resolution and running on a different device may mean it won't work properly. Some programs may only run in portrait or only in landscape mode, but others may detect the orientation of the screen and change the program accordingly. As each device may have a different screen resolution, a program set to run on one screen may not work on another size screen. Most modern apps are aware of the screen size/orientation and change but not every program does.

Home Screen

The main screen that Android shows is like a desktop on a pc. There are a number of screens (anything from three to seven), which you can switch between by swiping left or right. You have shortcuts to the programs you have installed, a background wallpaper, a notification and status bar showing the time and other info, programs that run on the desktop, known as widgets, and on screen buttons. As Android devices don't usually have keyboards, some features need an onscreen button. The three usual ones are Return, Home and Recent Apps. Some may have a fourth to the right used for menu options and the Tesco Hudl has a T on the left hand side to access their own apps. The on screen buttons are usually on the bottom, but the status/notification bar could be either at the bottom or top of the screen, depending on the device. The main home screen uses a launcher to start the programs, but you can install a different launcher to customise the look of your device.

Wallpaper

The background for the screens can be a colour or a wallpaper. The wallpaper is an image or an animation, usually called a Live Wallpaper. There are some included with the operating system, but you can install other ones that range from scenes, computer animations, animals, videos or anything. As with any app there are free ones and ones you have to pay for. Some programs will allow a different wallpaper for each screen whilst others can show the camera feed making the desktop effectively transparent.

Screen Grab

While some versions of Android can enable a screen grab button to let you get a screenshot, there are some button combinations you can use to grab an image of the screen. On a Hudl you press the power button and volume down button together until you hear a camera sound and see an image created. On my mobile phone it's the home button and power button together. The screenshots are usually stored on the internal memory in a fodler called Screenshots or a sub folder of one called Pictures.