A religious order is an organization of people who live in some way set apart from society in accordance with religious devotion. The members of such orders, termed religious as a group, are usually distinct from both the laity and the clergy. They are often termed monks, friars or brothers if male, and nuns or sisters if female.
Some orders practice literal isolation (cloistering) from the outside world; others remain engaged with the world in various ways, often teaching or serving in traditional roles, while maintaining their distinction in other ways. All, however, may be distinguished by vows or disciplines they undertake as members of their orders.
In Buddhist societies such as Sri Lanka, Thailand, Korea and Tibet, there exist strikingly large monastic orders. A well-known Chinese Buddhist order is the ancient Shaolin order in Ch'an (Zen) Buddhism.
Catholic religious orders should be distinguished from Holy Orders, the sacrament of bishops, priests, and deacons. The following list refers to Roman Catholic orders; it should be understood that communities using the same name may exist in Anglican or Eastern Orthodox traditions as well.
In the following list of some of the major Catholic orders, each order is listed with the acronym (or "post-nominal initials") commonly used to identify its members.