A patio (from the Latin "pactum" through the Occitan "pàtu") is an unroofed area located inside a building.[1]​ It can be considered a rear space of a house.

The patio can be surrounded by walls that separate it from other neighboring patios or from the public road, or completely surrounded by the rest of the parts of the same building. In any case it will be an area without a roof, optionally covered with porches, interior galleries with columns, beams or arches to support the structure of the shed "Tinglado (shed)").

In tall residential buildings, interior spaces or "light patios" are created to illuminate interior rooms that have windows. The back of the patio can be private (annexed to the ground floor home) or communal, either as an accessible common area, or closed for security reasons. These patios can coincide with other analogues of neighboring buildings and even have one side open to the street to obtain greater lighting.

The floor of the patios can be paved, or have a garden area. In any case, it usually has a drainage or rainwater evacuation system to prevent its accumulation. Roman houses (domus) used to have a water tank, or impluvium, which was filled directly with rain.[2]​.

In Andalusia,[3]​ the architectural fusion of the Roman and Muslim world has generated over the centuries a particular culture of patios that in many localities manifests itself every spring with festivals and competitions to encourage their care and decoration. The patio competition in Córdoba and the La Cruz de Mayo festivities in Seville are especially celebrated.

The elemental design of the patios in the basic architecture of the Roman house developed throughout the Middle Ages a type of home-hacienda around a large patio or corral. In the "Villa (population)" villas of southern Europe, this structure in turn served as a stage space giving rise to the corrales de comedias, large patios surrounded by galleries. Today we find in Almagro (Ciudad Real) one of the most representative of the century and the only one completely preserved. In the 19th century, this structure was magnified in the large neighborhood corralas of cities such as the capital of Spain. In 2007, there were still around five hundred corralas in Madrid, mainly in the neighborhoods of Lavapiés, La Latina and Palacio "Palacio (Madrid)").[4]​.