Britain is a big island that's part of Europe. It's made up of three countries - England, Scotland and Wales - and some smaller islands too. People have lived in Britain for a long, long time - even longer than your grandpa or grandma's grandma or grandpa! Lots of different groups of people have come and gone over the years, like the Celts, the Romans and the Vikings!
Britain has lots of cool things to see and do, like the Tower of London where they keep the crown jewels, the Scottish Highlands where you can see big mountains and lots of sheep, and Stonehenge where there are really big rocks that people put there a long, long time ago.
Sometimes you might hear people talk about 'Great Britain' - that's just a fancy name for the island with all the countries on it. People from Britain also sometimes call themselves British, and they might eat things like fish and chips or drink lots of tea.