This day represents one of the strongest sales day. Sales on this day spike usually because of last minute shoppers for the festival season that follows.
Online retailers usually take few days to deliver the purchase. So in order to get their product on time online consumers order few days before the Christmas. This day was observed as one of the days on which sales spike and thus it was named “Green” to represent the flow of money on this day.
Retailers provide many attractive offers and discount to consumers on this day. This term is more relevant for the online retail stores than brick or mortar retails. This phenomenon is similar to other such phenomenon like cyber Monday and Green Tuesday.