Celibacy is the abstention from sexual activity. Usually, the word is used to describe abstention from all sexual activity for religious purposes. The Roman Catholic Church requires this of priests in the Latin Rite (the post-Vatican II "New Mass" and the most popular throughout the world) and Tridentine Rite (the pre-Vatican II "Latin Mass" used by some churches). Celibacy is not a requirement for priests of other rites (including Eastern Rite Catholics), or already-married Anglican priests who convert to Catholicism, though priests cannot marry after the death of their spouse (this has always been the case with deacons as well).