It is known as Black Friday, and is the day the US, and increasingly the UK, goes mad for a bargain.
The traditional shopping frenzy takes place the day after Thanksgiving and marks the beginning of the Christmas shopping season, with an estimated 147 million people in the US expected to hit the shops.
The name of the day is thought to originate from the fact it marks retailers moving from the red into the black again.
The festival of spending is also usually marked by complete bedlam in stores across the US as shoppers battle to steal a bargain.
Early reports suggest there has already been fighting in some shops.
Experts expect online spending alone to rocket by 10 per cent, and even the UK is unlikely to be unaffected with Britons expected to spend around £200m online.
Last year Apple offered deals on its products cutting prices by up to 10 percent.
Retailers in the UK who have a price guarantee, such a John Lewis, will have to match the price drops.
Due to the fragility of the US economy this year the day is of special importance to retailers.
This was indicated by the fact many shops opened their sales on Thursday night.
When Macy's opened its doors in New York City at midnight, 11,000 shoppers showed up.
Target Corp. opened its doors at 9 p.m. three hours earlier than last year.
Sears, which didn't open on Thanksgiving last year, opened at 8 p.m.
Elizabeth Garcia, a sales rep from New York City, went shopping at about 3:30 a.m. at a nearby Toys R Us in Times Square.
Garcia, who has three children ages three, five and seven, said she specifically decided on the late time to avoid the crowds on Thanksgiving when the store opened at 8 p.m.
She believes that was the best decision: Last year, Garcia almost got into a fight over a Tinker Bell couch, but this year things were much calmer.
"This year I wasn't about to kill people," she said.
Are shoppers abandoning their children in the dash for a bargain?
A thread on the website Reddit has been set up discussing how some shoppers appear to be leaving their children unattended in car parks as they hunt for a bargain.
One post on the site said: "Work at a police station, already got a call like this last night. Woman parked her van in a handicapped spot and went to the store. Her very young children were so confused and upset they began asking passers by for help."
Another appeared to show a picture of children abandoned outside a store. And yet another user posted: "More Black Friday child neglect: Around 1AM my boss was walking through the parking lot to our store in the mall and witnessed a child no older than 2 years "hanging out of a car".