system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do you have to put in your debit pin in person, but not online?
gpt
The Idea of a PIN as a cardholder verification method relies on the two sets of data involved (card number and PIN) not being transmitted in the same way.  

For online websites, it's easier to use some other form of verifying the cardholder, such as with a billing address, CVC2 code, or two factor authentication, than to create some standardized way of transmitting pins in a secure fashion separate from the card number.