system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Early Credit Card Tech

How did credit card tech work pre internet days?
gpt
There was this machine that would take an imprint of the raised numbers on the card using carbon paper (it was a kind of paper that had ink which copied onto another paper when you pressed on it). You’d run the credit card and the triplicate receipt through a machine that pushed down on them in order to create copies. Then you’d sign and that too would go on all the copies. You’d get a copy, the store would get two—one for their records and one to send to the credit card company.