MINNEAPOLIS —  Long regarded as a mere curiosity to bricks-and-mortar shopping, online retailing has exploded during this year’s holiday shopping season, surprising even the most optimistic of retail observers.

“Personally, I don’t understand why a lot of people don’t shop online more,” said Cole Robertson, 25, a student at Winona State University in Winona, Minn. “The selection is broader, you can sit in your living room, and everything gets delivered to your doorstep.”

While traditional in-store purchases generate the vast majority of retailers’ annual sales, the pace of e-commerce has surged .. From Nov. 1 to Nov. 28, digital sales soared 15 percent to $15 billion from the same period in 2010, according to comScore.

On Black Friday alone, sales jumped 26 percent to more than $1 billion, while Cyber Monday pulled in another $1.25 billion.

And recent data suggest December is off to a good start. As of Dec. 7, Internet sales were up 27 percent from the same point in 2010, according to the Chase Paymentech Cyber Holiday Pulse Index.

Some analysts are convinced that online holiday shopping has crossed a threshold of sorts, in which Internet sales have become an end unto themselves and not just a way to grab a few leftover dollars that eluded stores.

“We’re at the tipping point,” said Mike Moriarty, a partner in the retail practice at global management consulting firm A.T. Kearney. “If I ever doubted the Internet changed my life, this is the year that it did.”
There are several reasons behind this surge.

•  Internet shopping is convenient, especially for those unwilling or unable to brave bad weather and long lines. Throw in free shipping, as Amazon.com and Walmart have done, and shoppers are running out of reasons to leave their homes.

•  Retailers are doing a better job at e-commerce, both from a technical and marketing standpoint.
For the most part, retailers’ websites and mobile software performed well during the Black Friday crunch, said Nisheeth Mohan, a senior product manager at Keynote Systems Inc., a firm that monitors retail websites.

Online promotions  have also become more sophisticated.  

Robertson, the student, says retailers offer better – and longer-lasting – deals online than Black Friday’s familiar door busters.

“Almost everything that I ‘liked’ on Facebook had deals through the week ranging from 25 to 75 percent off ,” Robertson said.

Except for Costco, which boasts no restocking fees, and the Apple Store, which offers great service, Clint Rasschaert, 37, of Minnetrista, Minn., who works in finance, says he sees almost no reason to visit traditional stores.

“I go into a bookstore and don’t find what I’m looking for,” he said. “I go to Amazon and, bam, it’s there, delivered for free, and I don’t pay taxes.”