Great Lent, or the Great Fast, is the most important fasting season in the church year in Eastern Christianity, which prepares Christians for the greatest feast of the church year, Pascha (Easter). In many ways Great Lent is similar to Lent in Western Christianity. There are some differences in the timing of Lent (besides calculating the date of Easter) and how it is practiced, both liturgically in the public worship of the church and individually.

One difference between Eastern Christianity and Western Christianity is the calculation of the date of Easter (see Computus). Most years, the Eastern Pascha falls after the Western Easter, and it may be as much as five weeks later; occasionally, the two dates coincide. Like Western Lent, Great Lent itself lasts for forty days, but unlike the West, Sundays are included in the count. Great Lent officially begins on Clean Monday, seven weeks before Pascha (Ash Wednesday is not observed in Eastern Christianity) and runs for 40 contiguous days, concluding with the Presanctified Liturgy on Friday of the Sixth Week. The next day is called Lazarus Saturday, the day before Palm Sunday. However, fasting continues throughout the following week, known as Passion Week or Holy Week, and does not end until after the Paschal Vigil early in the morning of Pascha (Easter Sunday).

Green Monday is an online retail industry term similar to Cyber Monday. The term was coined by eBay to describe its best sales day in December^[1], traditionally the 2nd Monday of December. Green Monday is defined more specifically by business research organization comScore as the Monday with at least 10 days prior to Christmas. In 2009, $854 million was spent online in the US on Green Monday,^[2] with sales in 2011 reaching $1.133 billion. ^[3]Green Monday in Greece and Cyprus is the movable feast day known elsewhere in the Greek Orthodox Church as Clean Monday, the first day of Lent - approximately seven weeks before Easter. Traditionally families go to fields to barbecue fasting foods such as vegetables and seafood (not meat), later flying kites and playing other games.

Green Monday also refers to a network of sustainable development practitioners in the UK, which meets on the first Monday of every month in London to discuss critical environmental issues affecting business and industry. Climate change is a major theme.^[4]