It is the day before Good Friday which takes place during Holy Week. It commemorates Jesus Christ’s last supper and the initiation of Holy Communion (the Eucharist), observed in many Christian churches.
It is the day when Christians commemorate Jesus Christ's crucifixion, which plays an important part in our Christian faith. It is not a federal holiday in the United States, although it is a state holiday in some states.
Pentecost is a Christian holy day commemorating the descent of the Holy Ghost upon the disciples of Jesus Christ, according to the New Testament of the Bible. It is also known as Whitsunday, or Whit Sunday.
Trinity Sunday is the first Sunday after Pentecost and is celebrated by many Christians in the United States. It is one of the few feasts that are celebrated as a doctrine instead of an event. It is also symbolic of the unity of the Trinity.