1. The modern use of the term "Black Friday" originated in Philadelphia in 1966, according to several published reports, including Time magazine. It was a term Philadelphia Police used to describe mobs of shoppers and gridlocked downtown traffic the day after Thanksgiving.

2. Around 1980, Black Friday came to be known as the day retailers ended the red ink of sales losses and moved into the black ink of profit, according to Mother Jones magazine.

3. The original use of the term dates back to the Sept. 24, 1864, stock-market panic triggered by plunging gold prices.

4. Black Friday has only recently become the busiest shopping day of the year. Between 1991 to 2001 it didn't rank in the top five. The Saturday before Christmas ranked as No. 1, according to Shoppertrack.com.

5. Many major retailers this year started sales before Black Friday, including on Thanksgiving day. Many employers now give employees the day after Thanksgiving off. The exception is in retail, where more employees are now required to work on Thanksgiving and show up in the middle of the night for shoppers.