Retailers are ringing in after-Christmas sales. Here's what to know about Amazon, Walmart and more.

This holiday shopping season saw Americans stepping up their purchases at retail stores, with many chains luring shoppers with big Black Friday discounts. But with the holiday now over, retailers are beginning to roll out their post-Christmas sales, aiming to entice shoppers to spend more.

Shoppers spent between $979.5 billion and $989 billion last month, while retail sales rose 2.5% to 3.5% in December from a year ago, according to an estimate from the National Retail Federation, the nation's biggest retail trade group. 

Retailers are now looking to encourage more of the same in wrapping up the holidays with additional post-Christmas promotions. This year's shorter holiday shopping period placed pressure on some retailers, some of which also struggled to attract inflation-weary consumers through their doors.