Quick aside. After writing about common HTTP status codes the other day, I figured out that I should also write about common methods and headers. So here is methods part.
Methods indicate action that should be performed on resource.
Requests specified resource. It should only retrieve data.
Submits data to server. Often causing side effects like saving to database or similar.
Updates specified resource with data from request.
Deletes specified resource.
Same as GET, just response doesn't contain body.
There are others, but they are almost never used. You can learn about them on MDN. Also, there are new server architectures like GraphQL that use POST for everything. Seems like HTTP methods will be less and less important in the future. We'll see!