Native-language identification is like a game where you try to figure out which language someone is best at speaking just by listening to them talk.
Think about your friends or family members who speak different languages. When they speak, you can usually tell which language they're speaking just by listening to the way the words sound.
Native-language identification is when machines (like computers) try to do the same thing. They listen to someone speaking and try to figure out which language they speak best.
This can be really useful in many ways. For example, if you're learning a new language, a machine that can identify your native language can provide more personalized, targeted feedback to help you learn better.
But figuring out someone's native language just by listening is really hard! Machines use a lot of different tools and techniques to try to do this. They look at things like the patterns of sounds and the way people use grammar and vocabulary in different languages.
It's still not perfect, but scientists and engineers are working hard to improve native-language identification so that it can be used for more and more useful things.