You’ve seen all the signs and adverts, had your inbox flooded with emails offering “massive discounts” and “unmissable deals”. There’s no escaping Black Friday. Falling on 25 November this year, Black Friday originated in the United States. The day follows the US Thanksgiving holiday (the fourth Thursday in November) and is seen as the start of the holiday season with shoppers hoping to snap up bargains and save on their Christmas shopping.But how does the discount day compare with other retail bonanzas? “In just three short years, Black Friday has radically reshaped consumer spending over the Christmas period in the UK,” says John Watton, of tech firm Adobe.On Black Friday we’re expected to spend about £2bn this year, with over half of this forecast to be spent online, according to the retail association IMRG and SimilarWeb. And it’s not just Black Friday. Cyber Monday has emerged as a way of persuading consumers to find the same online bargains a few days later. Over the four-day Black Friday/Cyber Monday weekend, shoppers are set to spend £4bn, predicts credit card provider MBNA. Over the Black Friday week, between 21-28 November, online spending could reach £6.77bn, say IMRG and SimilarWeb. This year’s Black Friday could also be boosted by shoppers trying to beat Brexit-induced price rises early next year, according to John Robert, the chief executive of online white goods retailer AO World.“With Brexit currency movements, prices are going up early next year, so there is a double whammy for customers. So our belief is it will be bigger than ever.” Despite the rigmarole of giving presents and cooking a Christmas dinner, many of us still find time to take a break from the festivities and turn to our smartphones for a bit of light retail therapy – even at the risk of annoying our relatives. While Christmas Day may be less important in terms of overall sales than either Black Friday or Cyber Monday, shoppers spend more money via their smartphones on 25 December than on the other two days – no matter which country you are from, says Adobe. Probably not that surprising though, given most shops on the High Street are closed on Christmas Day.The Christmas and January sales have traditionally been the most lucrative for High Street retailers, but in recent years Black Friday has changed all that and some analysts say this is also dragging some spending forward from the post-Christmas period.If so, it seems to have had little impact so far. Last year in the UK shoppers spent £3.74bn in the Boxing Day sales, according to figures from VoucherCodes.co.uk and the Centre for Retail Research – a 6% increase on 2014. Stores never used to open on 26 December – and there is currently a petition calling for them to shut again to give hard-pressed shop workers time to be with their families. Nowadays, Boxing Day sales tend to merge with what used to be just January sales, helping firms sell the seasonal goods they had left in warehouses and on their shelves.But not everyone in the shops is spending money – Boxing Day is many people’s favourite day to return unwanted Christmas presents.We’ve been celebrating love in mid-February for more than 2,000 years, yet it wasn’t until the 18th Century that people in Britain started sending cards or flowers to their beloveds, and commerce got going.Nowadays, just under half of us spend money on our Valentines – whether on flowers, chocolates, romantic dinners or other gifts – and we post about 25 million cards. But there are some suggestions that we are in two minds about it.While this year we spent about £980m (up slightly on 2015), more than three-quarters of consumers think it has become too commercial and more than half think it is a waste of money, according to a survey by retail analysts Verdict Retail.“Perceptions of Valentine’s Day becoming too commercial are in many ways a result of greater participation from the retailers. As well as wider choice from the ‘Big Four’ grocers, the discount players Aldi and Lidl, as well as value retailers like Poundland and B&M now offer big ranges,” says Verdict’s Greg Bromley. Halloween in the UK may not be as big as it is in the US but it is still becoming an increasingly important event for retailers. Consumers spent some £310m on Halloween tricks and treats in 2015, compared with £295m the year before, according to market research group Mintel.