This year's Cyber Monday sales were up at least 19 percent from last year, with about a third of all online shopping traffic coming from mobile devices. And while it's not as big as Black Friday, Cyber Monday's increasing year-to-year sales stands in contrast to this year's "gloomy" Black Friday sales drop of $1.7 billion compared to 2012. 

The widely-cited Cyber Monday figures above come from IBM Digital Analytics Benchmark, who noted in a press release that mobile traffic increased by at least 55 percent over last year. Taken together, they estimate, this year's Cyber Monday was the "biggest online shopping day in history." The mobile traffic boost was more dramatic for online stores that are more mobile-friendly: Walmart, for instance, saw 55 percent of its Cyber Monday traffic overall from mobile devices. IBM also explains that while more potential shoppers browsed retail sites on smartphones than on tablets, a higher percentage of actual purchases comes from tablet traffic. 

At least some retailers catered their Cyber Monday pitches to potential mobile customers, too: IBM reports a 77 percent increase in retail "push" notifications over the five-day shopathon period between Thanksgiving and Cyber Monday, compared to other, normal, shopping days. And more people are opting in to the apps that might deliver those notifications — the ones that pop up as an alert on your phone. Compared to a normal day, retail app installations were up 29 percent. 

Unsurprisingly, sales were way up at both Amazon and Ebay: Amazon's Cyber Monday sales were 47 percent higher than last years, and Ebay's were at least 21 percent higher, according to Bloomberg

Monday's sales are still small compared directly to Black Friday, even as its year-to-year numbers weaken. In 2013, sales totaled $57.4 billion on Friday, while early estimates of this year's Cyber Monday pull peg the total sales at about $2 billion. But especially as Black Friday sales decline, it should be clear by now that Cyber Monday (and a lot of other days for shopping online) has thoroughly caught on.