Facebook is like a big online club where people from all around the world can meet and talk to each other. It's on the internet, so anyone with the internet can use it. People use Facebook to stay in touch with friends and family, even if they live far away. To be part of Facebook, you need to have the internet, then you make an account by telling them some personal information and making a secret password to keep your stuff private.
When you're a member of Facebook, you can look for your friends and people you care about online, and you can invite them to be your friend on Facebook. Once they say yes, you're officially friends on Facebook, and you can share things like pictures and messages with each other on there. Facebook also lets you make different albums for your pictures and upload all sorts of things like photos and documents. You can even make friends with lots of different people.
On Facebook, you can write comments on your own stuff and other people's stuff, like their pictures or posts. You can also talk to your friends in real-time using the chat feature. One cool thing about Facebook is that if you've lost touch with someone for a long time, you can use it to find them again, as long as they're also on Facebook.
People also use Facebook to tell others about important things and share news. But there are some problems with Facebook too. Sometimes, bad people might post things that are rude or not nice. Other than those bad things, Facebook has really changed the way we live nowadays.