How does the payment system work on websites?

Question

Payment systems

I read about this topic, but did not quite understand how it works. As far as I understand, payment systems have an API, the client wanted to buy a product and fills out a form and the completed form, for example, is sent via a post-request to the payment system, where money is transferred from the buyer's account to the seller's account, do I understand correctly that this is how it works now?

Answer 1

You can do it in different ways:
you can simply redirect the buyer to the page of the payment system.
you can make a payment on your site without redirects and transitions to third-party sites