Because caching is part of the HTTP spec. If content doesn't change on every request, you cache it with a timeout. If users are looking at your site from around

Because caching is part of the HTTP spec. If content doesn't change on every request, you cache it with a timeout. If users are looking at your site from around the world, you want the cache to exist as close to them as possible. This is the job of the CDN. In Cloudflare's case, they sit between your web server and the user and can be that HTTP cache. If your site is popular, you might still have multiple versions of it across regions.