In this article, the authors present the results from a structured review of the literature, identifying and analyzing the most quoted and dominant definitions of social media (SM) and alternative terms that were used between 1994 and 2019 to identify their major applications. Similarities and differences in the definitions are highlighted to provide guidelines for researchers and managers who use results from previous research to further study SM or to find practical applications. In other words, when reading an article about SM, it is essential to understand how the researchers defined SM and how results from articles that use different definitions can be compared. This article is intended to act as a guideline for readers of those articles.