While the modern definition of Black Friday as a huge discount shopping holiday goes back to the 1980s, Cyber Monday is a relatively newly branded occasion. Nevertheless, sales on the online shopping holiday have skyrocketed since its introduction just over a decade ago, and its biggest moments could be yet to come.

Cyber Monday developed quite naturally as online sales on the Monday following the Thanksgiving holiday had spiked in the several years prior to the naming of the new holiday. The term itself was a reaction by the retail trade group known as the National Retail Federation (NRF) to the trend that was already occurring. It saw an opportunity to brand the new shopping occasion to accompany Black Friday.

"Seventy-seven percent of online retailers said that their sales increased substantially on the Monday after Thanksgiving, a trend that is driving serious online discounts and promotions on Cyber Monday this year," the group trumpeted the new holiday in late November 2005.

The New York Times subsequently noted the trend, giving Cyber Monday its first mainstream media mention. The publicity blitz succeeded, and online sales on the day shot up 26 percent from the year before, almost hitting the half billion-dollar mark.

Similar gains were seen for several years following, until a new web-shopping trend emerged, with online shoppers hitting the virtual stores earlier over the holiday weekend, not wanting to wait until Monday. Growth slowed for several years as the financial crisis hit, but then rebounded in 2010 as Cyber Monday sales passed the $1 billion milestone.

By 2012, Cyber Monday grew into Cyber Week, with many online retailers extending the discounts and bargains deeper into the holiday season. By 2013, sales surpassed $2 billion, spurred on by the increased use of mobile devices to shop online.

So what's in store for Cyber Monday 2015?

The NRF — yes, the same group that invented the Cyber Monday term in 2005 — predicts the number of people shopping online this year could reach nearly 184 million and will top the figures of those who shopped over the entire four-day Thanksgiving weekend.

Mobile growth is expected to continue to push Cyber Monday sales above the $3 billion mark for the first time, marking another important milestone in the short history of the shopping holiday known as Cyber Monday.