Online retail spending in the United States topped $1 billion for the first time on November 23, a day when many Americans began their shopping for the holiday season, up 26 percent from a year earlier. "Black Friday," as the day after Thanksgiving is known, is traditionally when retailers begin to turn a profit ("in the black"). Online sales are expected to be up 20 percent year over year throughout the holiday weekend, culminating in "Cyber Monday" with an estimated $1.5 billion in online purchases.

Overall, in-store and online sales combined were $59.1 billion over the four-day weekend, up 12.8 percent over 2011. A record 247 million shoppers made purchases, each spending an average $423. Retailers opened stores earlier and expanded layaway and discounts to attract shoppers.

Though crowds of shoppers showed up to score deals at physical stores over the holiday, the real story of the 2012 holiday shopping season is the ascendency of online shopping. As mobile technology improves, more shoppers are using their smartphones and tablets to skip the lines and shop in the comfort of their own homes. The National Retail Federation found that the average consumer spent $172.42 online over the weekend – "approximately 40.7 of their total weekend spending, up from 37.8 percent last year." Mobile devices accounted for about 26 percent of visits to retail websites and 16 percent of purchases on Black Friday.

Amazon.com was the most-visited retail website on Black Friday, along with Wal-Mart's website, Best Buy, Target and Apple, according to comScore Inc. Digital content and subscriptions, for example e-books, music and video, was the fastest-growing online retail category, with sales up 29 percent over last year.

"Online has been around 9 percent of total holiday sales, but it could breach 10 percent for the first time this season," Scot Wingo, chief executive of online retail consultants ChannelAdvisor, told the Huffington Post.

The author is a freelance writer living in New York City