Affiliate marketing allows people to earn money by promoting other companies' products and driving sales. Marketers earn commissions when visitors they refer purchase something. The affiliate marketing industry is large and growing, projected to be a $6.8 billion business in the United States by 2020. Successful affiliate marketers can earn millions by building an audience and recommending popular products through blogs, videos, and other content. Affiliate marketing provides opportunities to earn passive income anytime from anywhere by referring others to products and services online.