Google Hangouts, Google's communications platform, was announced two years earlier, also at Google I/O.
It includes basic social networking services like a profile photo, about section, background photo, cover photo, previous work and school history, interests, places lived and an area to post status updates.
It also includes several identity service sections, such as a contributor and other profiles area that let one link their "properties across the web". Organization of circles is done through a drag-and-drop interface.
Another function of Circles is to control the content of one's Stream.
A user may click on a Circle on the left side of the page and the Stream portion of the page (the center) will contain only posts shared by users in that Circle.
In an interview with Steven Levy published on May 28, 2015, Horowitz said that Google was about to undergo a "huge shift" that would better reflect how the service is actually used.