The shopping blow-out takes place the day after American Thanksgiving, which is always held on a Thursday.

It marks the beginning of the frenzied Christmas shopping season, as prices are slashed and millions descend on the high street to hunt down a bargain. Queues of hundreds pounding on the doors of big retailers is not an uncommon sight, and sometimes the hordes get violent.

In the past, there have been cases of stabbings, fighting and trampling, as stampedes overtake the high street. In 2008, a Wal Mart employee in New York was fatally injured in stampede.

According to the National Retail Federation, up to 140 million people across America will descend on shops today. Last year, keen shoppers spent an estimated $11.2billion on Black Friday.

Some say the term ‘Black Friday,’ originated to illustrate the point at which shops ‘go into the black,’ or make a profit. Others say it came from the code term Philadelphia police used to describe the overcrowded high streets and shopping stampedes that are common at this time of year.