"Black Friday is the day following Thanksgiving Day in the United States, traditionally the beginning of the Christmas shopping season. On this day many U.S. retailers open very early, often at 5 a.m., and offer promotional sales to kick off the shopping season. Because Thanksgiving always falls on the fourth Thursday in November in the United States, the day after occurs between the 23rd and the 29th of November.
The day's name originated in Philadelphia, where it originally was used to describe the heavy and disruptive pedestrian and vehicle traffic which would occur on the day after Thanksgiving. Use of the term began by 1966 and began to see broader use outside Philadelphia around 1975. Later an alternative explanation began to be offered: that "Black Friday" indicates the period during which retailers are turning a profit, or "in the black."