TGfU Google+ User profile is a public visible account that is attached to many Google properties. It includes basic social networking elements like a profile photo, about section, background photo, previous work and school history, interests, places lived and an area to post status updates.
Circles is a core feature of the Google+ Social Platform. It enable users to organize people into groups or lists for sharing across various Google products and services. Once a circle is created, a Google+ user can share specific private content to only that circle, Work themed content can be shared with only work colleagues, family could sees more personal content and photos for example. The option to share Public or with Everyone is always available.
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. For the unsegmented Stream (includes content from all of a user's Circles), each Circle has a "slider" configuration item with four positions: nothing, some things, most things, and everything. The nothing position requires the user to select (click on) the Circle name explicitly to see content from users in that Circle. The everything setting as its name implies filters nothing out from people in that Circle. The remaining two positions control the quantity of posts which appear in one's main Stream, but the algorithm controlling what shows has not been disclosed.
Hangouts are free video conferencing calls with up to 10 people, done through the Google+ website or mobile app. Many apps can be used inside the hangout, allowing users to share documents, a scratchpad or their screens with other users. As well as many built-in apps such as YouTube, Google Docs, and the new Capture. 3rd Party apps built using the Hangout API are also available
Hangouts On-Air gives users the ability to create instant webcasts over Google+. The broadcasts can also be recorded for later retrieval.