Good Friday

Good Friday is a Christian holiday commemorating the crucifixion of Jesus and his death at Calvary. It 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. Wikipedia

Why is it called "good"?

"...according to Fiona MacPherson, senior editor at the Oxford English Dictionary, the adjective traditionally "designates a day on (or sometimes a season in) which religious observance is held". The OED states that "good" in this context refers to "a day or season observed as holy by the church", hence the greeting "good tide" at Christmas or on Shrove Tuesday. In addition to Good Friday, there is also a less well-known Good Wednesday, namely the Wednesday before Easter."