E-commerce is particularly important during the holidays as online sales penetration spikes in the fourth quarter. This year will not be an exception. UPS predicts the number of packages shipped the hectic week before Christmas will hit 120 million— up 6.2% from last year—due entirely to growth in online shopping. Bain predicts e-commerce as defined by the Census Bureau will likely reach 5.6% of total retail sales in the fourth quarter of 2011. Excluding autos, fuel and gas stations and select other categories, that figure will be closer to 10%.

Omnichannel Retailing,” Darrell Rigby, Kris Miller and Josh Chernoff, bain.com