Black Friday is now one of the UK's busiest shopping days.
Retailers offer up a dizzying array of special offers and big discounts, with more deals added online on Cyber Monday.
But how can you spot a genuine bargain?
1 Check the size of the discount
Before you buy, it is always worth checking if the same product is cheaper somewhere else, experts say.
Some specialist sites can tell you if the product has been discounted more heavily before.
For example, Camelcamelcamel.com shows the price history of Amazon products - allowing shoppers to see if they have been offered more cheaply in the past.
When consumer group Which? looked back on retailers' offers last year, it found only 90 out of 178 deals were cheapest on Black Friday.
Danny Munday, general manager of HotUKDeals, a deal-sharing website, said retailers sometimes increase the price of an item before a sales event to make the discount look deeper.
Members in online forums will share their knowledge of sale prices and recommended retail prices, he added.
2 Look for price match
With competition fierce, retailers are starting to match the deals being offered by their rivals.
John Lewis is one of the main companies that does this, but Currys and Amazon also have in the past, said Gary Caffell, deal editor at MoneySavingExpert.
"When people are price matching each other, look at other factors like warranty and delivery fees," he said.
Electrical goods purchased from John Lewis often have longer warranties, compared with the standard one year.
That includes five years on televisions, three years on many own-brand electrical goods and two years on other electrical items.
Mr Caffell adds what all the experts agreed with: "Don't get sucked in by the hype and buy something you don't need or can't afford."
3 All-store discounts can offer better value
Retailers often have deals "up to" a big headline percentage, but only some stock will be available at that discount.
"The stronger deals are those which are available across the whole store," Mr Caffell said.
For example, Gap is offering a 40% discount on full-price items and the Disney Store has 20% off.
One thing to be aware of with big Black Friday discounts on certain items is that sometimes they are unwanted stock which is of poor quality, Mr Munday said.
It is also worth looking out for extra discount codes on companies' Facebook pages or mailing lists, for example on delivery charges, they said.
4 Know your rights
Experts also cautioned that some Black Friday bargains might be non-refundable.
"Online you've got the right to change your mind and take it back, but that's not necessarily the case in-store," Mr Caffell said.
Research by Which? indicates only 29% of shoppers know that they have more protection when returning goods bought online than in-store.
"It's important to do your research so you know your shopping rights before you buy, just in case you change your mind," said Alex Neill, Which? managing director of home and legal.
Jo Causon, chief executive of the Institute of Customer Service, said customers are increasingly thinking about the shopping experience and aftercare, not just price.
"If you're having to take things back and it's difficult, that's hardly a bargain," she said.
5 Brace for website crashes
Once you've found a bargain online, though, you do not want to lose it because the website or app crashes.
Sites including John Lewis, Argos and Tesco Direct have struggled with the traffic in previous years.
In some cases the websites have crashed but are still available on mobile or tablet, Mr Caffell said.
By having a page open across multiple devices, you are better protected from crashes, he said. It also gives you an extra place in online queues, which can be very long.
"The busiest time for people logging on is going to be around midnight and then 08:00 or 09:00 in the morning," Mr Caffell said.