Browsing the web - Learn web development | MDN

I really like this explanation of what happens in between the user entering a web address into the browser and the browser displaying the result.

1. The web browser requests the resource you want to access from the web server it is stored on.
2. If the request is successful, the web server sends a response back to the web browser containing the requested resource.
3. In some cases, the requested resource will then fire off more requests, which will result in more responses.
4. When all of the resources have been requested, the web browser parses and renders them as required, before displaying the result to the user.