Pentecost is the Greek name for the Feast of Weeks, a prominent feast in the calendar of ancient Israel celebrating the giving of the Law on Sinai. This feast is still celebrated in Judaism as Shavuot. Later, in the Christian liturgical year, it became a feast commemorating the descent of the Holy Spirit upon the Apostles and other followers of Jesus Christ, (120 in all) as described in the Acts of the Apostles 2:1–31. For this reason, Pentecost is sometimes described by some Christians today as the "Birthday of the Church." In the Eastern church, Pentecost can also refer to the whole fifty days between Easter and Pentecost, hence the book containing the liturgical texts for Paschaltide is called the Pentecostarion. The feast is also called White Sunday, or Whitsun, especially in England, where the following Monday was traditionally a public holiday. Pentecost is celebrated seven weeks (50 days) after Easter Sunday, hence its name. Pentecost falls on the tenth day after Ascension Thursday. The Pentecostal movement of Christianity derives its name from the New Testament event. In Italy it was customary to scatter rose petals from the ceiling of the churches to recall the miracle of the fiery tongues; hence in Sicily and elsewhere in Italy Whitsunday is called Pasqua rosatum. The Italian name Pasqua rossa comes from the red colours of the vestments used on Whitsunday. In France it was customary to blow trumpets during Divine service, to recall the sound of the mighty wind which accompanied the Descent of the Holy Spirit. In the north west of England, church and chapel parades called Whit Walks take place at Whitsun (sometimes on Whit Friday, the Friday after Whitsun). Typically, the parades contain brass bands and choirs; girls attending are dressed in white. Traditionally, Whit Fairs (sometimes called Whitsun Ales) took place. Other customs such as morris dancing and cheese rolling are also associated with Whitsun. Since Pentecost itself is on a Sunday, it is automatically a public holiday in Christian countries. Additional restrictions to Sunday opening hours may apply.

Source:Wikipedia