A post office is a facility authorized by a postal system for the posting, receipt, sortation, handling, transmission or delivery of mail.• Post offices offer mail-related services such as post office boxes, postage and packaging supplies. In addition, some post offices offer non-postal services such as passport applications and other government forms, money orders, and banking services.

Post offices also rent post-office boxes to people and businesses who prefer not to have mail delivered to their home or office, or who live or stay at addresses to which mail delivery is not available.

The back rooms of a post office are where mail is processed for delivery. Mail may also be processed in other post offices that are not open to the general public.

The '''Post Office''' is a retail company in the United Kingdom; formerly part of the postal service Royal Mail, it became a separate entity in 1981.