Black Friday is the discount shopping day that has to do with the American Thanksgiving, which is always on a Thursday. Retailers promote this day as the day to start shopping for Christmas. BlackFriday is often advertised with "Christmas Sales" as well as "Thanksgiving Sales."
The word "black" in Black Friday refers to the term "in the black" meaning making a profit. Today, Black Friday is not a crucial source of profit to retailers, but is important in driving traffic into stores. Many retailers mail special Black Friday circulars to consumers, announcing deeply discounted items in the hopes that consumers will visit their store on Black Friday.