Orthodox Pentecost Sunday, also known as Holy Spirit Sunday, is observed seven weeks after Orthodox Easter.
The date in the Orthodox church will differ from the Western church due to the different methods of calculating the date of Easter.
Orthodox Pentecost Sunday is also known as ‘Kneeling Sunday’, as it is tradition not to kneel during prayers in the church from Easter Sunday until Pentecost Sunday.
It marks the end of the Easter cycle, that began 92 days before with Orthodox Shrove Monday.
Pentecost Sunday commemorates the coming of the Holy Spirit in the form of flames to the Apostles, as recorded in the New Testament in Acts, 2.
The Holy Spirit allowed the apostles to speak in other languages, and they started preaching the word of Jesus to the Jews who come to Jerusalem for the feast of Shavuot (Pentecost). Many Christians recognize this event as the birth of the Church.
The following day, Pentecost Monday, is celebrated as a holiday in some East European counties.
In Eastern Orthodox Christianity, Pentecost can refer to the entire period of the fifty days of Easter through to Pentecost.