Worldwide online retail sales totaled 1.9 trillion in 2016 and it's estimated that revenues will hit 4 trillion by 2020. Even a microscopic share of this market can make anyone rich, yet most everyone who tries to make money online fails. The Digital Marketing Handbook was written to help marketers of all skill levels -- from Fortune 1000 and SMBs to small business owners and solopreneurs -- take their websites from cost centers to profit centers.