By shrinking the keyboard in this way we soon had to grapple with a basic fact:human input is imprecise, and the faster you type the more imprecise it gets. Rather than trying to improve user precision, we instead embrace sloppy typing.

This only works because we use disambiguation in addition to auto-correction. While “auto-correction” implies that you made a mistake that needed correcting, “disambiguation” accepts the fundamental ambiguity of human interaction, and uses an understanding of language to narrow things down. Think of it like speech recognition: in a noisy bar, the problem isn’t that your friends are speaking incorrectly; human speech is ambiguous, and the noisiness of the environment sure doesn’t help. You can only understand them because you have prior knowledge of the sorts of things they are likely to say.

Source: http://minuum.com/model-your-users-algor...