Membership numbers of social networking websites

Facebook
General purpose business, professional, and social networking
845,000,000+  members
Open to people 13 and older

Linked In
Business and professional networking
120,000,000 members
Open to people 18 and older

Google+ Members
General purpose business, professional, and social networking
100,000,000 members
Open to general public

Read more or revise source via List of social networking websites – Wikipedia, the free encyclopedia.