Google+ (or Google Plus) is a social networking service created by Google. Google Plus is a service which comes with all google services including Gmail and Youtube. It is the 5th largest social network in the world with 540 million monthly active users.
Google+ is unique as it is also Google's identity service so users must have a Google+ account in order to register or access all google services Therefore the 540 million monthly active users are for the identity service and not the social network itself.
Google+ has various features including: User profiles, Circles, Stream, Hangouts and Hangouts On Air, The +1 Button, Google+ Pages and Communities. It also had a "What's Hot" section that shows current trending and recommended content to users. A lot of functionality on the site can be compared with features on Facebook, such as the "+1" feature and the user profiles layout - however, Google+ has additional features such as being able to sort added into custom groups such as "Acquaintances" and "Friends" using the Circles feature.
Google launched the Google+ testing phase in June 2011 but had to suspend the invitations to do a large demand. Shortly after Google gave each Google+ member 150 invitations to test the service before launching it to all over 18 year olds in September of the same year. Since its launch, Google+ has grown exponentially to having 540 million users as of 2013. The website has, however, received criticism for its forceful integration with other Google services, leaving users of these services with no choice but to create an unused profile. It also was poorly received when the social network was used as the basis for the updated YouTube comments section.