The document discusses the emergence of hybrid media and social media in the 1990s and 2000s. It introduces concepts around social media including how influencers shape social trends and how influence can be tracked through large amounts of social media data. However, influence on social media can raise legal and ethical issues for businesses like potential economic harm from inaccurate reviews. The document also discusses theories related to how people use social media like uses and gratification theory and gatekeeping, as well as challenges and solutions for companies using social media.