A Circle is an interest or an association that is used to organize people and activities. Circles can be anything, but in general we encourage adding Circles that represent people or activities you would like to share with others.
When you become a member of a Circle, you can participate in activities shared with that Circle or share your own activities with the Circle. Only your connections can see what you share to a Circle. Optionally, you can share with 2nd degree connections (friends-of-friends).
Here are the different types of Circles: