What’s the difference between a POS and other transactions?

A POS transaction requires that you key the PIN on a keypad at the cash register. It also posts immediately to your account. A VISA check card charge, or debit charge, either generates a receipt for you to sign, or is a transaction done over the phone or online. VISA check card transactions do not post immediately to the account, but the funds from the transaction are on hold (unavailable) until the charge posts.