Like the Order of St. Benedict, it is not one legal body, but a union of various independent congregations. Though they also follow the Rule of St. Augustine, they differ from the friars in not committing themselves to corporate poverty, which is a defining element of the mendicant orders. Unlike the friars and like monks, the canons are generally organized as one large community to which they are attached for life with a vow of stability. Their houses are given the title of an abbey, from which the canons then tend to various surrounding towns and villages for spiritual services. The religious superior of their major houses is titled an abbot. Smaller communities are headed by a prior or provost.