Shops have started to slash prices and offer discounts for the annual bargain frenzy Black Friday.

And this year's event could become the UK's first £1 billion online shopping day.

The shopping weekend that starts on Black Friday and culminates in Cyber Monday has become big business in the UK, with many shoppers waiting to begin their Christmas shopping when prices are cut.

Online retailers are braced for a shopper onslaught from midnight on Friday as deals go live, while some stores will open their doors from the early morning to customers hoping to snatch bargains on everything from TVs to slippers.

If you are hoping to get in on the bargains then we've rounded up key information including when Black Friday is and who is expected to slash prices.

When is Black Friday?

Black Friday is on November 27 but shoppers have seen deals offered online and in shops from Monday, November 23.

Online retailers are braced for shoppers to go online at midnight as deals go live, while some stores will open their doors earlier than normal.

Why is it called Black Friday?

There are different theories behind the name but a popular one is that it means prosperity.

When shops would mark down earnings it would show gains in black ink and losses in red ink.

What's the story behind Black Friday?

What a Tesco store looked like last year
What a Tesco store looked like last year

It is a massive sales tradition in the US. It's the Friday after Thanksgiving and said to be the day that shoppers begin their shopping for Christmas.

It was introduced here in 2010 in the UK and some retail experts say it is changing the way we shop.

The deals and discounts offered on Black Friday are similar to the Boxing Day sales and an increasing number of shoppers are holding out to bag bargains on this day.

Will it be busy?

Yes! Last year there were queues out the door at Tesco stores, hours before the event began.

Tesco will be opening at 5am this year though, whereas last year they threw open their doors at midnight.

It is thought that shoppers are holding out for great deals so you can expect your town or city centre to be pretty packed. If you're not sure that's for you then you can find deals online at most places.

Which shops will be offering Black Friday deals?

Amazon, Argos, Boots, Carphone Warehouse, Currys, FeelUnique.com, Halfords, Homebase and Matalan are among the stores offering Black Friday deals and they have already started slashing prices.

Apple, ASOS, British Airways , Carphone Warehouse, Disney store, eBay, Game, House of Fraser, Lakeland, Maplin, Selfridges, Superdrug Toys R Us, and very.co.uk were all involved in 2014 and expected to join in this year too.

Some of the big names taking part include Apple, Amazon UK, Argos, Currys PC World, Game, Marks & Spencer, John Lewis, Tesco but you should expect most high street stores to offer discounts in some way.

You can see how the event unfolded in our live blog from last year to get an idea of the kinds of discounts to expect.

However, Asda have decided they won't take part in Black Friday this year, instead offering deals from now until the New Year.

Bosses say they will step back from the sales because of "shopper fatigue setting in around flash sales on big-ticket, non-essential items at Christmas.

Read More: Get the most out of seasonal deals this year .

How can I prepare for Black Friday?

Shoppers in Tesco last year
Shoppers in Tesco last year

Make sure you set a budget and have a shop around before the sales start.

You may see some good deals in the run-up to the shopping event so make sure you keep an eye out, but retailers don't usually release a list of deals before Black Friday so you'll need to be on the ball.

If you know what you're after then it helps to sign up to alerts from retailers you plan to buy from and create online accounts on those websites to speed up the process.

What sort of deals can I expect from the retailers?

Amazon

Amazon.co.uk say the website is gearing up for its busiest week of the year with the return of Black Friday Deals Week, which will feature more than 7,000 offers.

For the first time, hundreds of UK-based Amazon Marketplace sellers have been invited to participate in Black Friday Deals Week, providing customers with an even larger selection of deals.

It starts at midnight on Monday, November 23 and runs until 11.59pm on Sunday, November 29.

Shoppers will be offered ‘Lightning Deals’ – products available at a discount, in limited quantities, for a short period of time - as well as ‘Deals of the Day’ – selected products on offer for one day, from 00:01 to 11:59pm.

In addition to the Black Friday Deals Week offers on Amazon.co.uk, selected deals will be available through Prime Now, Amazon’s app that offers one-hour delivery to Prime customers. These offers will be available to eligible addresses in London and Birmingham from 8am to midnight.

Last year, sales on Amazon.co.uk peaked at 8.29am on Black Friday.

The most popular deals in 2014 included the Kindle Fire HDX 7” range with £100 off selected models, as well as the Dolce Gusto Mini Me Coffee Capsule Machine, Toy Story Ultimate Action Buzz Lightyear, diamond jewellery and men’s watches.

Deals last year include a men's Citizen quartz watch for £69 down from £229, an Ariel 18ct white gold and diamond necklace reduced from £12,995 to £6,995 and a £99.99 Panasonic bread maker on sale for £69.99.

Read More : Our pick of the best XBOX One, PS4 and Nintendo deals .

Apple

It is thought that the technology giant Apple will offer a range of discounts in UK stores on Black Friday. However, if you want to get good deals on Apple products, money saving expert Martin Lewis says the big retailers that sell these items may be your best bet.

Argos

Argos say if you register for an Argos account before Black Friday you will get quicker access to their biggest deals and faster in-store collection from their fast track counter in-store when you buy online. They will also hold your item for seven days so you can pick it up at a convenient time.

They say if you want to avoid the rush then 3-4 am was their quietest period online last year - so set your alarm!

Argos launched their Red, White and Blue Fridays deals, in the run up to Black Friday and all the offers are available for seven days in-store and online.

Currys PC World

You can register your interest on the website so you won't miss a thing. And the retailer says that if you find the same item for a cheaper price at any of their major competitors then they will match it. To help you keep track of prices they have created a free price comparison app that tracks their prices and those of their leading competitors. They say all the prices are checked by an independent source.

In the meantime, thousands of promotions are already under way in its Black Tag Event.

Game

Game stores across the country opened at midnight for Black Friday and they have listed midnight openings on their website again for 2015. They say "when they're gone, they're gone!"

They also have countdown deals in the run-up to the event.

John Lewis

John Lewis will be taking part in Black Friday
John Lewis will be taking part in Black Friday

John Lewis' commitment to being “Never Knowingly Undersold” means it will price match competitors’ deals. They also tend to discount lots of individual and popular items and last year offered money off the popular NutriBullet.

So keep an eye out online from midnight online on Black Friday and in store from 8am.

Johnsons Dry Cleaners

There will be a two for one offer starting Friday on all dry cleaning.

Morrisons

You can buy a magnum of prosecco for £10 in store.

Tesco

Last year Tesco had great deals on TVs, PS4s and X-Boxes, iPads, toys and furniture. This year they say they are increasing their stock so expect more of the same. Participating stores will open at 5am and there will also be online deals from midnight.

Last year a lot of people turned up to queue from 6pm until midnight at one Cardiff Tesco, and it was a similar scene at many stores around the country. Even scuffles broke out at one Cardiff branch. This year they say they have increased online stock and added security and barriers at various stores as required.

Topman

There are different deals throughout the week. The one for Tuesday, November 24 for example was half price key seasonal pieces and free earphones with every £60 order.