Google+ opened its doors to the public on September 20 after 12 weeks of invite-only beta testing. During that time, despite limited signup allowances, Google’s social network exploded in popularity. In late July, the site notched its 25 millionth new account, prompting ComScore to declared it the fastest-growing social network ever.
The site continues to add members, but it’s still dwarfed by the user pools of more established networks like Facebook, Twitter and LinkedIn. Facebook, the mother of all social networks, in September boasted over 800 million active accounts. LinkedIn reported way back in March 2011 that it had accumulated 100 million users, and Twitter’s recent figures numbered its user accounts at 100 million.