Bluetooth keyboard
Some people hate the onscreen keyboard of a tablet or find it suffices for only short bursts of typing. The answer to that is a Bluetooth keyboard. You can use any Bluetooth keyboard with an iOS or Android device, but you'll prefer one designed for your OS to get its specific keys. Get one that protects the keys so that they aren't damaged in transit.
I prefer Logitech's Tablet Keyboard (available for iOS and for Android) because of its sturdy protective sleeve that doubles as a stand.
Many users love the Zagg Keyboard Case for iPad. It protects both your keyboard and your iPad's screen, and it works as a stand.
