How does the Back button in a web browser work?

Question

I searched the Web about this question but I found nothing:

What is the logic of the back button? What is happening when we hit the back button on a Web browser?

Answer 1

As a devoloper, you should make sure that your webapp works no matter how the browser handles the Back button :-) Does it resend the request? Is the new request identical to the old one, or does it differ in any way? Will browser ask user to confirm re-POST? What elements of the page will be re-requested and what loaded from cache? Will browser respect my cache-control headers?

Answers to these question depend on make, version of a browser and user settings. Design you software so that all this doesn’t matter that much.

Sorry for not very direct answer, but there are some straight answers here already.