Back Button (Browser Behavior)

Question

When the back button is pressed in a web browser, is the default action to send a get request or serve from the browsers history?

If its browser specific, what would

Answer 1

I just tested this in Chrome and Firefox for fun

When I press back in Chrome on a Google search page, no requests happen. The browser pulls from cache.

In Firefox, I actually get a 204 No Content with the path being http://clients1.google.ca/generate_204 from Google.

I found this using Charles proxy so it's nothing scientific :)