Good Friday, also known as Holy Friday, Black Friday, Great 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.

Based on Christian scriptural details of the Sanhedrin Trial of Jesus, the Crucifixion of Jesus was most probably on a Friday (BibleverseJohn19:42KJV). The estimated year of Good Friday 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 (consistent with Apostle Peters reference to a "moon of blood" in Acts 2:20 (Acts of the Apostles)) points to Friday, 3 April AD 33.