The Dictionary

As you type on your Android phone, the keyboard will auto correct as you type. In the case of unrecognized words, the built in dictionary can save anything you type in its memory. This way, the next time you type a personal abbreviation or unrecognized word, it won't try and autocorrect it.
If you mistakenly save a misspelled word, you can go back into the personal dictionary and edit or remove the word entirely. It will then be autocorrected to the word you specify.