A postmaster is the head of an individual post office, responsible for all postal activities in a specific post office. When a postmaster is responsible for an entire mail distribution organization, the title of Postmaster General is commonly used. Responsibilities of a postmaster typically include management of a centralized mail distribution facility, establishment of letter carrier routes, supervision of letter carriers and clerks, and enforcement of the organization's rules and procedures. The postmaster is the representative of the Postmaster General in that post office.

A post office is a public facility and a retailer that provides mail services, such as accepting letters and parcels, providing post office boxes, and selling postage stamps, packaging, and stationery. Post offices may offer additional services, which vary by country. These include providing and accepting government forms, and processing government services and fees. The chief administrator of a post office is called a postmaster.