Predictive text is an input technology that is designed to facilitate typing by suggesting words based on the first letters typed, in the context of other words in the message.
The earliest common application for predictive text was for text messaging. T9 (text on 9 keys) uses predictive text to make typing on mobile phones and other small devices easier than it is with multi-tapping, which requires the user to tap numbers up to four times to register some characters. Predictive text is used on smartphones, tablets and other mobile devices.
Although predictive text technologies are becoming increasingly sophisticated, the software is still notoriously error-prone. Erroneous predictive text input is sometimes referred to as the Cupertino effect or an auto-correct fail.