Maundy Thursday is the Christian holy day that falls on the Thursday before Easter. It honors the Last Supper of Jesus Christ with the Apostles and foot washing (Maundy) as described in the canonical gospels. It is the fifth day of Holy Week that is preceded by Holy Wednesday and followed by Good Friday. "Maun-" is from Old Norse that present of munu meaning shall or will; akin to Old English and gemynd meaning mind.
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 date is always between March 19 and April 22 inclusive but these dates fall on different days depending on whether the Gregorian calendar or Julian calendar is used liturgically. Easter Triduum is initiated by the liturgy held on the evening of Maundy Thursday. It is the period which honors the resurrection, death and passion 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 generally celebrated in the evening when Friday begins according to Jewish tradition. It is because according to the three Synoptic Gospels, the Last Supper was held on the feast of Passover.