Chip (also known as Chip and PIN) cards [j.mp/wichpin] are a good example of a protective proxy used in real life. The debit/credit card contains a chip that first needs to be read by the ATM or card reader. After the chip is verified, a password (PIN) is required to complete the transaction. This means that you cannot make any transactions without physically presenting the card and knowing the PIN.

A bank check that is used instead of cash to make purchases and deals is an example of a remote proxy. The check gives access to a bank account. The following figure, courtesy of sourcemaking.com, shows how a check acts as a remote proxy [j.mp/proxypat]: