A liturgy is a ceremony, according to the traditions of a particular group or event. In religion, it may mean an elaborate formal ritual (such as the Catholic Mass), or a daily activity such as the Muslim Salats. Anglican, Orthodox, Lutheran, or other groups, when using the words "the liturgy", normally mean a standardized order of events observed during a religious service, often including the Eucharist or Communion. The "open" or "waiting" worship of Quakers is an example of a non-liturgical service because there is no structured order of events.