So imagine you have two neighbors who live in different houses but in the same street. One, let's call it the United States, is a big house with many rooms and a big yard where there's always a lot of things going on, like playing sports or having barbecues. The other neighbor, Canada, lives in a smaller house with a beautiful garden but not as much activity.
Some people in Canada have been talking about joining the big house of the United States, because they think it would be more fun to have more people to play with and a bigger space to do it in. But not everyone in Canada agrees, some people really like their pretty garden and don't want to give it up.
This talk of annexation has been going on for a long time, but most people think it's not very likely to happen because Canada has its own government and laws, and it's a separate country from the United States. It's kind of like you having your own toys and your neighbor having theirs, even though you live in the same street, your toys are yours and your neighbors are theirs. They are two separate things.
So even though some people might like the idea of joining the United States, most Canadians feel proud of their own country and want to keep it that way.