This document discusses three commercial uses for social media: 1) Advertising on platforms like Facebook, Twitter, and Instagram which have millions of users paying to advertise their products and services. 2) Viral marketing techniques that allow content to be easily shared across social networks to reach wider audiences. Examples include games, ebooks, and videos. 3) Product and service reviews posted by customers on sites like TripAdvisor, which businesses monitor to improve based on customer feedback.