Maundy Thursday April 22 inclusive, but these dates fall on different days depending on whether the Gregorian calendar or Julian calendar is used liturgically. Eastern churches generally use the Julian calendar and celebrate this feast throughout the 21st century between April 1 and May 5 in the more commonly used Gregorian calendar. The liturgy held on the evening of Maundy Thursday initiates the Easter Triduum, the period which commemorates the passion, death, and resurrection of Jesus; this period includes Good Friday and Holy Saturday, and ends on the evening of Easter. The Mass of the Lord's Supper or service of worship is
Foot washing "mandatum" (maundy), therefore, was applied to the rite of foot-washing on this day of the Christian Holy Week called Maundy Thursday. John 13:1–17 recounts Jesus' performance of this act. In verses 13:14–17, He instructs His disciples: Many denominations (including Anglicans, Lutherans, Methodists, Presbyterians, Mennonites, and Catholics) therefore observe the liturgical washing of the feet on Maundy Thursday of Holy Week. Moreover, for some denominations, foot-washing was an example, a pattern. Many groups throughout Church history and many modern denominations have practiced foot washing as a church ordinance including Adventists, Anabaptists, Baptists, and Pentecostals. The origin of the word "Maundy" has