More and more shoppers are finding that online shopping offers greater convenience, lower prices, more information, and a more personalized user experience that makes buying online preferable to going to a store. And as free shipping becomes more common, one of the last remaining barriers to e-commerce is falling. The shift was reflected in this year’s Black Friday weekend numbers. Although sales were essentially flat overall, online sales grew as a share of total sales by 28 percent from the previous year.