Your web browser is designed on the assumption that you do not have access to unlimited bandwidth and your ISP either caps or charges if you use too much.

If you visit a page it keeps a copy in your Temporary Internet Files folder (the technical term is "cache")and displays that if you go back to the page rather than waste bandwidth. There are parameters on how long to cache pages in your browser set up.

If you think you may be viewing a cached page you can force your browser to go back across the web by pressing CTRL + F5