How to make a "Continue shopping" button?

Question

PHP

Please help
I need to make a "Back to shopping" button in the shopping cart. This button should return the site visitor to the page from which he went to the basket, how to make such a button? How to generate the necessary link in it?
The engine is self-written

Answer 1

Google REFERER:
echo $_SERVER["HTTP_REFERER"];

Answer 2

It’s easier not to do it from the basket, but through pop-up when adding goods to the basket. Divide into 2 buttons like "go to cart" and "continue shopping"