A gated community is a form of residential community or housing estate containing strictly controlled entrances for pedestrians, bicycles, and automobiles, and often characterized by a closed perimeter of walls and fences. Historically, cities have built defensive city walls and controlled gates to protect their inhabitants, and such fortifications have also separated quarters of some cities. Today, gated communities usually consist of small residential streets and include various shared amenities. For smaller communities, these amenities may include only a park or other common area. For larger communities, it may be possible for residents to stay within the community for most daily activities. Gated communities are a type of common interest development, but are distinct from intentional communities.

A defensive wall is a fortification usually used to protect a city, town or other settlement from potential aggressors. The walls can range from simple palisades or earthworks to extensive military fortifications with towers, bastions and gates for access to the city. From ancient to modern times, they were used to enclose settlements. Generally, these are referred to as city walls or town walls, although there were also walls, such as the Great Wall of China, Walls of Benin, Hadrian's Wall, Anastasian Wall, and the Atlantic Wall, which extended far beyond the borders of a city and were used to enclose regions or mark territorial boundaries. In mountainous terrain, defensive walls such as letzis were used in combination with castles to seal valleys from potential attack. Beyond their defensive utility, many walls also had important symbolic functions – representing the status and independence of the communities they embraced.