How does google checkout know the site an item was purchased from?

: How does google checkout know what site an item was purchased from?
I went to a website on the net to purchase a few products, and there was a google checkout option. I clicked and made the purchase. How does google know that it was from site A from site B?

Answers and Views:

Answer by Bouriaulis
If you’re signed into Google at the time you added the items to your cart, and the website that you purchased your items from has a Google Checkout option, then it will automatically know which site you bought it from.

So pretty much if you’re signed into Google, and any site that has Google options (which is pretty much anything) Google will track it. But don’t worry, nothing is personal tracking, unless you’re doing something illegal (which they still probably wouldn’t track you).