The predictive keyboard works like a full-size keyboard, but uses a dictionary to resolve miskeying on the small board. As you tap, words appear above the keyboard. If you tap on the middle, bold one you will accept that word. If you tap on the other options, they will switch to the middle. If there are many potential words for your input, you may need to press an alternative on one side several times to find your word.
For more information on adding or removing words from the dictionary, see Words
Capital letters are entered by stroking upwards on the keyboard to reveal the capital letters board, which functions just like the lowercase board. Note that the hints bar will show the capitalisation in the dictionary, but the keyboard will remember which letters you entered as capitals. Stroking up again shows the Symbol board. Because the dictionary cannot be used to resolve ambiguities on the symbol board, it only accepts the press-and-hold style input. The last board is the number board. This can be reached by stroking up on the symbol board or down from the lowercase board, and contains numbers. Numbers also do not use the dictionary prediction.