Aug 29, 2012
Google+ is a multilingual social networking and identity service owned and operated by Google Inc.

It was launched in June 28, 2011. As of June 2012, it has a total of 250 million registered users of whom 150 million are active. Unlike other conventional social networks which are generally accessed through a single website, Google has described Google+ as a "social layer" consisting of not just a single site, but rather an overarching "layer" which covers many of its online properties.

Google+ originally launched as Google Circles, a name alluding to its emphasis on organising friendship information. The service was launched as an invitation-only "field test" in June 2011. Early invites were soon suspended due to an "insane demand" for new accounts. On September 20, 2011, Google+ was opened to everyone 18 years of age or older without the need for an invitation. It was opened for a younger age group (13+ years old in US and most countries, 14+ in South Korea and Spain, 16+ in Netherlands) on January 26, 2012.

Source: Wikipedia