How does an online payment system work??

Think you typed into devRant instead of google.

@helloworld I've always been curious on this. I have searched it. Wanted to know developers perspective....

It's complex... really complex!! Don't even think about implementing one on your own!! Instead use the PayPal API or the Stripe SDK

I really wanted to do the SpongeBob "magic" gif, but you are serious.
(Short Version)
Card Number, Name, Expiration Date, Billing Address, Security Code (three digit on the back), and the sale total are encrypted and sent to the card company (based on the first digit of card number) or a clearing house. There it is decrypted and card approval is based on the first 4 to 10 of the card number based on some rules and cross checked with the last 4 with your name and address. If there is an approval the ack goes back to the site, and either the sale is batch or live processed to your account. The processor then subtracts the "swipe fee" (3% to 5%) from the sale total, keeps their fee and sends the rest to the store via an account setup by their agreement.

@helloworld 😂