Prime is a text input method. Prime homepage

It is a predictive text input method, designed originally for Japanese language input. What predictive means, is that based on your prior typing it predicts words that you want to type and proposes these to you.

It can be very well used with English as well.

You basically type the word, and as you type, you see the available options, once you see one of them, you select it with space and confirm with enter. If you don't see it, you just type the word as you'd like it to be typed, then confirm with double enter. From now on, it's gonna be offered as a candidate.

Once you get past a brief learning period, the text input is very fast.

How to install Prime