> - when I type in a URL in my browser's address bar, press Enter, and then the page appears, tell me what happened technically in as low level as possible.

Hey, that's one of my favorite questions as well! Great way to gauge depth of knowledge, and you can take it so many places afterwards (HTTPS / SSL, REST, etc).

The best answer I heard started with "well, the enter key press triggers an interrupt...., followed by discussion of browser / OS differences with respect to caching DNS info."