Good Friday is a religious holiday observed primarily by Christians commemorating the crucifixion of Jesus Christ and his death at Calvary. The holiday is observed during Holy Week as part of the Paschal Triduum on the Friday preceding Easter Sunday, and may coincide with the Jewish observance of Passover. It is also known as Holy Friday, Great Friday, Black Friday,or Easter Friday,though the latter properly refers to the Friday in Easter week. Based on the details of the Canonical gospels, the Crucifixion of Jesus was most likely to have been on a Friday (the day before the Sabbath) (John 19:42).The estimated year of the Crucifixion is AD 33, by two different groups, and originally as AD 34 by Isaac Newton via the differences between the Biblical and Julian calendars and the crescent of the moon.A third method, using a completely different astronomical approach based on a lunar Crucifixion darkness and eclipse model, points to Friday, 3 April AD 33.

Source:Wikipedia