Why store sessions on the server instead of inside a cookie?

Question

I have been using Flask for some time now and I am really enjoying the framework. One thing that I fail to understand is that in almost all other places they talk about storing

Answer 1

If the session data is needed at the server, it makes sense to store it at the server. It keeps down the data bulk sent back and forth from the client. Also, cookies have a limit on the amount of data they can store.