The definition of virtual communities varies, depending on the perspective from which they are considered. From a business perspective, Hagel and Armstrong (1997) define virtual communities as online groups of people with common interests and needs. Preece (2000) looks at virtual communities from the e-commerce perspective and argues that, according to e-commerce entrepreneurs, any communication software such as a bulletin board can be regarded as a virtual community. Balasubramanian and Mahajan (2001) consider the virtual community from an economical perspective, and they define them as any entity that exhibits the following characteristics:
It is made up of an aggregation of people.
Members are rational utility-maximizers.
Members interact with one another without physical collaboration; however, not every member must necessarily interact with every other member.
Members are engaged in a social-exchange process which includes mutual production and consumption. Each member is engaged in the consumption process; however, not everyone is involved in the production.
Social interactions between members revolve around a well-understood focus that encompasses a shared objective, shared property, or shared interest.