UK streets, shopping centres and online sites were awash with discounts today as more retailers than ever embraced US-style "Black Friday" promotions.

The Friday after Thanksgiving in the US is called Black Friday because spending usually surges and indicates the point at which US retailers begin to turn a profit for the year, or go "into the black". 

In Ireland, we tend to Christmas shop online the most from today until Monday December 1, known as Cyber Monday, the busiest online shopping day of the year. 

Visa predicts that $74m will be spent online by Irish shoppers this weekend. 

Though Amazon introduced Black Friday to Britain in 2010, last year marked the first time major UK store groups such as John Lewis, Dixons and Wal-Mart's Asda participated in a serious way. 

A survey commissioned by Barclays found that 65% of Britain's multi-channel retailers planned Black Friday promotions this year. 

This year new participants include Sainsbury's, Britain's third biggest grocer, which is offering cut price deals on 13 product lines, including TVs, tablets, audio products and kitchen electricals in 485 stores. 

Tesco, Britain's biggest retailer, has extended Black Friday promotions to selected stores, having only participated online last year. 

Marks & Spencer, the UK's biggest clothing retailer by sales, is also doing more this year, with all online deals, such as 30% off Autograph lingerie and men's coats, mirrored in store. 

Dixons and Argos have also ramped-up their offers. Asda said its event this year will be three times bigger than last year's, with 441 stores taking part. 

UK retail sales growth slowed slightly in November against a backdrop of smaller price rises, but retailers are upbeat about Christmas, figures from the Confederation of British Industry showed earlier this week. 

Whether embracing Black Friday makes commercial sense for UK retailers remains open to debate. 

Analysts say it can delay autumn sales, pull forward Christmas sales that store groups would otherwise have made at full price, can blunt sales in subsequent weeks and also leaves consumers expecting more pre-Christmas promotions. 

Some retailers have also been accused of inflating prices before then slashing them to give the appearance of bargains.