Sociedad Estatal de Correos y Telégrafos, S.A., popularly known as Correos, is the national postal service of Spain, as recognized by the Universal Postal Union. With 63,000 employees and 5.4 billion pieces of mail sent each year, Correos is one of the largest postal services in the world. Based in Madrid, it has over 10,000 postal centres all over Spain.

Correos has covered the whole of Spanish territory every day in public service for more than 300 years.

During the Middle Ages, the post belonged to the Crown. There was a long period of messengers, royal couriers, runners—like the 80 that the King of Aragón, Pedro el Ceremonioso, had—and of important positions related to correspondence, like the Main Post Office in the court of the Spanish Catholic Monarchs.

In the modern era, under the rule of the Habsburgs, the administration of the service was contracted to individuals and Correos started to have a more homogenous structure with a certain similarity to the current service. From 1506, Philip I bestowed the postal monopoly on Francisco Tassis who gave us the system and organisation that he himself had used in Germany. Juan Francisco Goyeneche was the last postal service contractor From the 18th century, with the accession of the Bourbons to the throne, Philip V made Correos into a state service available to all citizens. The service developed through detailed regulations (like those of 1720 and the Postal Orders of 1743) and through the men who managed Correos in the following years; men such as Rodríguez de Campomanes who from 1755 standardised charges, introduced home deliveries and created the post offices and post boxes in them (the precedents of local post) and improved the road network. These were just some of the reforms which led to the modernisation of the postal service in Spain.