Poste restante, also known as general delivery in North American English, is a service where the post office holds the mail until the recipient calls for it. It is a common destination for mail for people who are visiting a particular location and have no need, or no way, of having mail delivered directly to their place of residence at that time.

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.