Online, communities of people aggregate, sharing common interests, ideas, and feelings over the Internet. In this article we focus on the concept of so-called virtual communities (VCs) from a theoretical and empirical perspective. We want to provide a definition from desk research which can be useful on the theoretical and the empirical level. Moreover, we compare it with the definition that emerges from the interviews, which is typical from the qualitative approach perspective. Research questions (RQs) are: (1) How can a VC be defined? and (2) How is a VC defined by its users? We used Porter’s typology of VCs to select four case studies and conducted 49 in-depth interviews with their members. Our study points to the applicability and usefulness of Porter's typology of virtual communities and suggests a new approach for defining the concept VC.