Reply #20: From Wikipedia:

[Err]

Black Friday, the day after Thanksgiving in the United States, is historically one of the busiest retail shopping days of the year. Many consider it the "official" beginning to the Christmas shopping season. The "black" in the name comes from the standard accounting practice of using red ink to denote negative values (i.e., losses) and black ink to denote positive values (profits). Black Friday is the day when retailers traditionally get back "in the black" after operating "in the red" for the previous months.

Although Black Friday is typically the busiest shopping day of the year in terms of customer traffic, it is not typically the day with the highest sales volume. That is usually either the last Saturday before Christmas or December 23.

Because of the large amount of shopping that typically occurs on Black Friday, it has also become Buy Nothing Day.