Observed by many Christians, Pentecost commemorates the descent of the Holy Spirit upon the Apostles and women followers of Jesus, occurring on the seventh Sunday after Easter and 10 days after Ascension Thursday.

The word Pentecost suggests it occurred fifty days after the Passover, also known as the Feast of Weeks which was one of the major annual feasts at the time.

Shavot
Pentecost is derived from a Jewish harvest festival called Shavuot. The apostles were celebrating this festival when the Holy Spirit descended on them.

Acts 2:1-8

“And when the day of Pentecost was fully come, they were all with one accord in one place. And suddenly there came a sound from heaven as of a rushing mighty wind, and it filled all the house where they were sitting. And there appeared unto them cloven tongues like as of fire, and it sat upon each of them. And they were all filled with the Holy Ghost, and began to speak with other tongues, as the Spirit gave them utterance. And there were dwelling at Jerusalem Jews, devout men, out of every nation under heaven. Now when this was noised abroad, the multitude came together, and were confounded, because that every man heard them speak in his own language And they were all amazed and marveled, saying to one another, Behold, are not all these which speak Galilaeans? And how hear we every man in our own tongue, wherein we were born?”