Black Friday is over and done with and now retailers are getting ready for the last Saturday before Christmas. Dubbed Super Saturday, it could turn out to be the biggest shopping day of the year.

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Sales are expected to reach up to $10 billion on Super Saturday, compared to estimated Black Friday sales of $9.1 billion, according to ShopperTrak.

So what makes the Saturday before Christmas such a big day for shopping? For one, it gives people a chance to purchase gifts on a day when most are off from work.

"Regardless of the day Christmas falls on, people don't always take off of work on the days leading up to it, so they often take advantage of the last weekend before," said Dan Butler, senior adviser with the National Retail Federation (NRF).

Super Saturday is also an important day for retailers. Unlike in the past, retailers want to serve their customers however they want to be served.

"Maybe part of your shopping is done online and some of it is done in the store, however you as a consumer want to shop, the retailer wants to give you the service as best they can. So, we see a lot of promotion both online and in stores on Super Saturday," Butler said. "They know from history that the weekend before Christmas is always a heavy traffic day, so they prepare accordingly and promote accordingly."

Deals during the upcoming weekend will likely include specific discounts that will help rid stores of inventory and promote post-holiday sales.

"Since so many people give gift cards now, the 10 days after Christmas have also become very important shopping days, so retailers pay close attention to their promotional activity at that time too," Butler said.

Overall, the average person is expected to spend $804.42 on holiday gifts this year, up nearly 5 percent from 2013, according to a survey released on Oct. 16 by the NRF.