Shoppers on Black Friday, the traditional start of the holiday shopping season in America, are notoriously (声名狼藉的) aggressive. Some even start queuing outside stores before dawn to be the first to lay their hands on heavily discounted goods. Last year destructively violent bargain-hunters in the suburbs of New York City trampled (踩踏) a Wal-Mart employee to death. Despite the madness at many stores, however, the recession appears to have accelerated the pace at which shoppers are abandoning bricks and mortar (灰浆) in favour of online retailers—e-tailers. E-commerce holds particular appeal in poor times as it enables people to compare prices across retailers quickly and easily. Buyers can sometimes avoid local sales taxes online, and shipping is often free. No wonder, then, that online shopping continues to grow even as the offline sort shrinks. The shift in spending to the internet is good news for companies like P&G that lack retail outlets of their own. But it is a big concern for brick-and-mortar retailers, whose prices are often higher than those of e-tailers, since they must bear the extra expense of running stores. The most obvious response to the growth of e-tailing is for conventional retailers to redouble their own efforts online. The online arms of big retailers are performing well, on the whole. The concept of "multichannel" shopping, where people can buy the same items from the same retailer in several different ways, is gaining ground, and retailers are trying to encourage users of one channel to try another. Retailers are also trying to make shopping seem fun and exciting to act against the recession. One common method is to set up "pop-up" stores, which appear for a short time before vanishing again, to develop a sense of novelty and urgency. Stores are also trying to lure customers by offering services that are not available online. Best Buy, a consumer-electronics retailer, has started selling music lessons along with its musical instruments. Lululemon athletica, which sells sports clothes, offers free yoga classes. The idea is to bring people back to its shops regularly, increasing the likelihood that they will develop the habit of shopping there. Why does the author say the recession has accelerated the pace of online shopping