Christian monasticism is the devotional practice of Christians who live ascetic and typically cloistered lives that are dedicated to Christian worship. It began to develop early in the history of the Christian Church, modeled upon scriptural examples and ideals, including those in the Old Testament, but was not mandated as an institution in the scriptures. It has come to be regulated by religious rules (e. g. the Rule of Saint Augustine, Anthony the Great, St Pachomius, the Rule of St Basil, the Rule of St Benedict,) and, in modern times, the Canon law of the respective Christian denominations that have forms of monastic living. Those living the monastic life are known by the generic terms monks (men) and nuns (women). The word monk originated from the Greek μοναχός (monachos, 'monk'), itself from μόνος (monos) meaning 'alone'.

Christian monks did not live in monasteries at first, rather, they began by living alone as solitaries, as the word monos might suggest. As more people took on the lives of monks, living alone in the wilderness, they started to come together and model themselves after the original monks nearby. Quickly, the monks formed communities to further their ability to observe an ascetic life. According to Christianity historian Robert Louis Wilken, "By creating an alternate social structure within the Church they laid the foundations for one of the most enduring Christian institutions..." Monastics generally dwell in a monastery, whether they live there in a community (cenobites), or in seclusion (recluses).