Good Friday is the day of mourning for Christians. It is the day Christians commemorate the crucifixion of Jesus Christ and his death at Calvary. There are many theories about why such a sorrowful day should be called 'Good Friday'.
Some say it is called 'Good' because it is believed that Jesus Christ died on this day for the salvation of mankind. Others say 'Good' here is only another word for 'Sacred' as two days after this Friday, Easter is celebrated to express happiness on the resurrection of Christ from the dead.
Scholars believe Jesus was betrayed by his disciple Judas during the last supper. The event is accepted to have occurred in 33 AD. It is believed Jesus was on the cross from 9 am and died at 3 pm on that Friday.
That is the reason why Christians pray at 3 pm on Good Friday. It is also a day for either fasting and abstinence or modest eating. In some countries, Good Friday processions are carried out and prayer meets are held. It also marks the end of the 40 days of Lent and the arrival of Easter festivities on the following Sunday, to mark the rise of Christ.