What is a pre authorized purchase?

Question

I just checked my bank balance and found this on it. HOW DID THIS HAPPEN?

Answer 1

A pre-authorized purchase is established by a written agreement under which a financial institution is authorized by the customer to debit the customer's account in order to pay bills.

In other words, if you have any payments setup with any companies for "automatic charges", that is called a pre-authorized purchase.  You're allowing them to make the necessary charges on the given invoicing date.