Patriarch Kirill of Moscow and all Russia, who heads the Russian Orthodox Church, will lead the Easter divine service in Moscow's Christ the Savior Cathedral, due to start at 11 p.m. Moscow time (19:00 GMT). President Dmitry Medvedev and Prime Minister Vladimir Putin are expected to attend.
Easter celebrations begin on Holy Saturday evening with a long church vigil commemorating the buried Christ. The service culminates in a grand midnight procession with crosses and icons, which is often attended by nonbelievers attracted by its pageantry, and lasts into the early hours of Sunday.
Easter is Christianity's most important feast. According to the New Testament, Jesus Christ was resurrected on the third day after being crucified and dying on the cross to save people from sin.
The Resurrection of the Savior symbolizes the victory over sin and death and the birth of a new world redeemed by his Passion. After midnight and in the 40 days after Easter Sunday believers greet each other with "Christ is risen!" and the reply "He is risen indeed!" followed by three kisses and the exchange of Easter eggs.
Holy Saturday was preceded by Good Friday, considered the most sorrowful day of Holy Week and of the liturgical year.
The fasting period before Easter in Eastern Christianity lasts 48 days. The first 40 days of the period are called Lent, symbolizing Jesus spending 40 days in the wilderness being tempted by Satan.
They are followed by Lazarus Saturday, commemorating Jesus raising Lazarus of Bethany from the dead, and Palm Sunday, when Jesus entered Jerusalem, and then by Holy Week, the last week of the fasting period. Holy Week lasts until Easter Sunday but does not include it.
The purpose of the fasting period is for believers to prepare themselves, through prayer and fasting, for Easter.
This year, Roman Catholics and Protestants celebrated Easter on April 12 due to differences in the calendars used by Eastern and Western Christianity.
A group of pilgrims is expected to deliver the Holy Fire from Jerusalem to the central Russian cathedral. The Holy Fire that is lit every year at the Church of the Holy Sepulcher in Jerusalem on the day preceding Orthodox Easter is believed by Orthodox Christians to be a miracle.
From Moscow the Holy Fire, which pilgrims say does not burn in the first minutes after it has been lit, is "distributed" among churches in containers similar to those used to transport the Olympic flame.
Russia's other Easter traditions include painting and coloring eggs - normally red as a symbol of the blood of Christ - and cracking them on Sunday. The tradition of giving paschal eggs dates back to the first century A.D.
Church legend has it that Mary Magdalene came to Roman Emperor Tiberius with a preaching of faith and presented him with an ordinary chicken egg. Tiberius did not believe her story of the resurrected Christ and said: "How can anyone be risen from the dead? This is as impossible as if this egg became red now." And the egg turned red, showing the emperor the truth of the Christian faith.
Many Russians on Easter Sunday visit the graves of their late loved ones, a tradition tolerated but not condoned by the Church, which says Easter is a time of joy rather than sad reflection.