Nun, in strict Catholic canonical usage, denotes a woman religious belonging to an order of solemn vows, historically observing enclosure, cloister, a formal separation from the outside world governing a nun's movement and a monastery's own openness to visitors, and distinguishes such women from sisters, members of congregations of simple vows engaged in active ministries such as teaching, nursing or social work outside the monastery's walls; popular English usage collapses the distinction, calling any vowed Catholic religious woman a nun regardless of which canonical category she actually belongs to. Cloistered nuns, Carmelites, Poor Clares and Benedictine nuns among the most prominent orders, organize their life around communal prayer and contemplation, most orders supporting themselves through some combination of donations and enclosed work such as producing vestments, altar bread or other goods sold to support the community.
Degrees of enclosure vary by order and have been progressively relaxed since the Second Vatican Council, which encouraged religious communities to reconsider historical practices, including strict enclosure, in light of their founders' original charism and contemporary pastoral needs, though many contemplative communities of nuns have deliberately retained a substantial degree of separation from ordinary social life as central to their vocation's specific character rather than as an outdated restriction to be discarded.