Black Friday is the term coined for the day after Thanksgiving, traditionally the busiest shopping day of the year as retailers go from "being in the red," to making a profit, or "being in the black."

Surrounded by hundreds of shoppers grabbing bargain-priced flat-screen television sets and portable music players early yesterday morning, Jill Mulhere was trying to figure out what happened to her shopping cart, heaped with presents, at the Best Buy store in Paramus, N.J. …

''You know,'' she said, ''my brother asked me at Thanksgiving, 'Was there really all this Black Friday pandemonium when we were growing up?'''

Christmas decorations around Tampa Bay started going up in late October, and business has been brisk since then. And while Friday - known as Black Friday for the legendary hordes - will be the biggest shopping day for many area stores, others ring up the greatest sales the Saturday before Christmas.

For downtown merchants throughout the nation, the biggest shopping days normally are the two following Thanksgiving Day. Resulting traffic jams are an irksome problem to the police and, in Philadelphia, it became customary for officers to refer to the post-Thanksgiving days as Black Friday and Black Saturday.