Monasticism in Christianity is a family of similar traditions that began to develop early in the history of the Christian Church, modeled upon scriptural examples and ideals, but not mandated as an institution by the Scriptures.
While most people in the West, think of Christian monastic life--especially that of Catholic monks or nuns--as having "something to do with living in a monastery", from the Church's point of view, the focus has nothing to do with living in a monastery or performing any specific activity; rather, the focus is on an ideal called the religious life, also called the state of perfection. This idea is expressed everywhere that the things of God are sought above all other things, as seen for example in the Philokalia, a book of monastic writings. In other words, a monk or nun is a person who has vowed to follow not only the commandments of the Church, but also the evangelical counsels (e.g., vows of poverty, chastity, and obedience). The words of Jesus which are the cornerstone for this ideal are "be ye perfect like your heavenly Father is perfect".