Moveable feast in the context of "Date of Easter"

Pentecost (also called Whit Sunday, Whitsunday or Whitsun) is a Christian holiday that takes place on the 49th day (50th day when inclusive counting is used) after Easter. It commemorates the descent of the Holy Spirit upon the Apostles of Jesus, Mary, and other followers of the Christ, while they were in Jerusalem celebrating the Feast of Weeks, as described in the Acts of the Apostles (Acts 2:1–31). Pentecost marks the "Birthday of the Church".

Pentecost is one of the Great feasts in the Eastern Orthodox Church, a Solemnity in the Roman Rite of the Catholic Church, a Festival in the Lutheran Churches, and a Principal Feast in the Anglican Communion. Many Christian denominations provide a special liturgy for this holy celebration. Since its date depends on the date of Easter, Pentecost is a "moveable feast". The Monday after Pentecost is a legal holiday in many European, African and Caribbean countries.

Holy Week (Koine Greek: Ἁγία καὶ Μεγάλη Ἑβδομάς, romanized: Hagía kaì Megálē Hebdomás, lit. 'Holy and Great Week') commemorates the seven days leading up to Easter. It begins with the commemoration of Christ's triumphal entry into Jerusalem on Palm Sunday, marks the betrayal of Jesus on Spy Wednesday (Holy Wednesday), climaxing with the commemoration of the Last Supper on Maundy Thursday (Holy Thursday) and the Passion of Jesus on Good Friday (Holy Friday). Holy Week concludes with Christ's death and descent into hell on Holy Saturday. For all Christian traditions, it is a moveable observance. In Eastern Christianity, which also calls it Great Week, it is the week following Great Lent and Lazarus Saturday, starting on the evening of Palm Sunday and concluding on the evening of Great Saturday. In Western Christianity, Holy Week is the sixth and last week of Lent, beginning with Palm Sunday and concluding on Holy Saturday.

Christians believe that Jesus rested in death from the ninth hour (3 pm) on Good Friday until just before dawn on Sunday morning, the day of his resurrection from death, known as Easter Sunday. However, in 1 Peter 3:19, there may be a clue as to a task Jesus performed during this period between death and resurrection: "By which also he went and preached unto the spirits in prison." This marks the beginning of the season of Eastertide, with its first week being known as Easter Week (or Bright Week).

Whit Monday or Pentecost Monday, also known as Monday of the Holy Spirit, is the holiday celebrated the day after Pentecost, a moveable feast in the Christian liturgical calendar. It is moveable because it is determined by the date of Easter. In the Catholic Church, it is the Memorial of the Blessed Virgin Mary, Mother of the Church, marking the resumption of Ordinary Time.

Whit Monday gets its name from "Whitsunday", an English name for Pentecost, one of the three baptismal seasons. The origin of the name "Whit Sunday" is generally attributed to the white garments formerly worn by those newly baptised on this feast.

Lent (Latin: Quadragesima, 'Fortieth') is the solemn Christian religious observance in the liturgical year in preparation for Easter. It echoes the 40 days Jesus spent fasting in the desert and enduring temptation by Satan, according to the Gospels of Matthew, Mark and Luke, before beginning his public ministry. Lent is usually observed in the Catholic, Lutheran, Moravian, Anglican, United Protestant and Orthodox Christian traditions, among others. A number of Anabaptist, Baptist, Methodist, Reformed (including certain Continental Reformed, Presbyterian and Congregationalist churches), and nondenominational Christian churches also observe Lent, although many churches in these traditions do not.

Which days are enumerated as being part of Lent differs between denominations (see below), although in all of them Lent is described as lasting for a total duration of 40 days, the number of days Jesus, as well as Moses and Elijah, went without food in their respective fasts. In Lent-observing Western Christian denominations, Lent begins on Ash Wednesday and ends approximately six weeks later; depending on the Christian denomination and local custom, Lent concludes either on the evening of Maundy Thursday (Holy Thursday), or at sundown on Holy Saturday when the Easter Vigil is celebrated, though in either case, Lenten fasting observances are maintained until the evening of Holy Saturday. Sundays may or may not be excluded, depending on the denomination. In Eastern Christianity – including Eastern Orthodox, Eastern Catholics, Eastern Lutherans, and Oriental Orthodox – Great Lent is observed continuously without interruption for 40 days starting on Clean Monday and ending on Lazarus Saturday before Holy Week.

Palm Sunday is the Christian moveable feast that falls on the Sunday before Easter. The feast commemorates Christ's triumphal entry into Jerusalem, an event mentioned in each of the four canonical Gospels. Its name originates from the palm branches waved by the crowd to greet and honor Jesus Christ as he entered the city. Palm Sunday marks the first day of Holy Week; in Western Christianity, this is the beginning of the last week of the solemn season of Lent, preceding Eastertide, while in Eastern Christianity, Holy Week commences after the conclusion of Great Lent.

In most Christian rites, Palm Sunday is celebrated by the blessing and distribution of palm branches (or the branches of other native trees), representing the palm branches that the crowd scattered before Christ as he rode into Jerusalem. These palms are sometimes woven into crosses. The difficulty of procuring palms in unfavorable climates led to the substitution of branches of native trees, including box, olive, willow, and yew.

Shrove Tuesday (also known as Pancake Tuesday or Pancake Day) is the final day of Shrovetide, which marks the end of the pre-Lenten season. Lent begins the following day with Ash Wednesday. Shrove Tuesday is observed in many Christian countries through participating in confession, the ritual burning of the previous year's Holy Week palms, finalizing one's Lenten sacrifice, as well as eating pancakes and other sweets.

Shrove Tuesday is observed by many Christians, including Anglicans, Lutherans, Methodists, Western-rite Orthodox Christians, and Roman Catholics, who "make a special point of self-examination, of considering what wrongs they need to repent, and what amendments of life or areas of spiritual growth they especially need to ask God's help in dealing with." This moveable feast is determined by the date of Easter. The expression "Shrove Tuesday" comes from the word shrive, meaning absolution following confession. Christians traditionally visit their church on Shrove Tuesday to confess their sins and clean their soul, thus being shriven (absolved) before the start of Lent.

The Paschal Triduum or Easter Triduum (Latin: Triduum Paschale), Holy Triduum (Latin: Triduum Sacrum), or the Three Days, is the Christian period of three days that begins with the liturgy on the evening of Maundy Thursday, reaches its high point in the Easter Vigil, and closes with evening prayer on Easter Sunday. It is a moveable observance recalling the Passion, Crucifixion, Death, burial, and Resurrection of Jesus, as portrayed in the canonical Gospels.

In the Anglican, Lutheran, Methodist, Moravian and Reformed traditions, the Paschal Triduum straddles the two liturgical seasons of Lent and Easter in the Church calendar (Holy Saturday is the last day of Lent, with the Easter Vigil being the first liturgy of Eastertide). In the Roman Catholic tradition since the 1955 reform by Pope Pius XII, the Easter Triduum has been more clearly distinguished as a separate liturgical period.