A courtyard or court is a circumscribed area, often surrounded by a building or complex, that is open to the sky.

Courtyards are common elements in both Western and Eastern building patterns and have been used by both ancient and contemporary architects as a typical and traditional building feature. Such spaces in inns and public buildings were often the primary meeting places for some purposes, leading to the other meanings of court. Both of the words court and yard derive from the same root, meaning an enclosed space. See yard and garden for the relation of this set of words. In universities courtyards are often known as quadrangles.

Courtyards—private open spaces surrounded by walls or buildings—have been in use in residential architecture for almost as long as people have lived in constructed dwellings. The courtyard house makes its first appearance c. 6400–6000 BC (calibrated), in the Neolithic Yarmukian site at Sha'ar HaGolan, in the central Jordan Valley, on the northern bank of the Yarmouk River, giving the site a special significance in architectural history. Courtyards have historically been used for many purposes including cooking, sleeping, working, playing, gardening, and even places to keep animals.

Before courtyards, open fires were kept burning in a central place within a home, with only a small hole in the ceiling overhead to allow smoke to escape. Over time, these small openings were enlarged and eventually led to the development of the centralized open courtyard we know today. Courtyard homes have been designed and built throughout the world with many variations.

Courtyard homes are more prevalent in temperate climates, as an open central court can be an important aid to cooling house in warm weather. However, courtyard houses have been found in harsher climates as well for centuries. The comforts offered by a courtyard—air, light, privacy, security, and tranquility—are properties nearly universally desired in human housing. Almost all courtyards use natural elements.

Courtyards were widely used in the ancient Middle East. Middle Eastern courtyard houses reflect the nomadic influences of the region. Instead of officially designating rooms for cooking, sleeping, etc., these activities were relocated throughout the year as appropriate to accommodate the changes in temperature and the position of the sun. Often the flat rooftops of these structures were used for sleeping in warm weather. In some Islamic cultures, private courtyards provided the only outdoor space for women to relax unobserved. Convective cooling through transition spaces between multiple-courtyard buildings in the Middle East has also been observed.

In c. 2000 BC Ur, two-storey houses were constructed around an open square were built of fired brick. Kitchen, working, and public spaces were located on the ground floor, with private rooms located upstairs.

The central uncovered area in a Roman domus was referred to as an atrium. Today, we generally use the term courtyard to refer to such an area, reserving the word atrium to describe a glass-covered courtyard. Roman atrium houses were built side by side along the street. They were one-storey homes without windows that took in light from the entrance and from the central atrium. The hearth, which used to inhabit the centre of the home, was relocated, and the Roman atrium most often contained a central pool used to collect rainwater, called an impluvium. These homes frequently incorporated a second open-air area, the garden, which would be surrounded by Greek-style colonnades, forming a peristyle. This created a colonnaded walkway around the perimeter of the courtyard, which influenced monastic structures centuries later.