T9 (predictive algorithm)

T9 is a thing that helps you type faster on your phone. When you tap on the keys, it will try to guess what word you are trying to type, and put it up on the screen for you to choose. It does this by using some very smart stuff called an algorithm, which is like a recipe that tells the computer how to think.

So say your friend's name is "Sally". In the old days, you had to tap on the S, then the A, then search for the L.. but with T9 it will usually guess "Sally" after you type S-2-5-5-9. It can figure out what word you want to type by looking at the letters you've typed so far, and turning them into possible words.

The more you use it, the better it gets - it will start to remember the things you type most often and guess them faster next time. This can save you a lot of time and energy when you're typing out messages or emails, and it's especially helpful if you're not very good at spelling. So next time you use a phone with T9, remember that it's doing all the hard work for you!