Thursday, December 13, 2012, 7:30 p.m.; Sunday, December 17, 2012, 7:30 a.m. E-commerce and online sales have revolutionized holiday shopping. First there was the rise of Cyber Monday, but now the growth of mobile and tablet-based commerce makes it easier than ever to shop from anywhere at any time. Social media has accelerated this process, with consumers sharing shopping tips with friends and retailers offering special deals.