Great Lent is an Eastern Orthodox holiday which always begins on a Monday between February 15 and March 21. The beginning date, Clean Monday, is set at seven weeks before Pascha, or Easter, in the Orthodox church. Great Lent is so named to differentiate it from the Advent fasting period which is known as Little Lent.
Great Lent is a period of self-denial and is observed with strict abstinence from meat, dairy products, wine, and olive oil. Orthodox Christians also make a sacrifice during this period such as giving up a favorite food or other pleasure.