Sending an invitation to someone to become a "friend" on Facebook or other social networking site. If the individual accepts, they have access to each other's information and updates. Users can even friend a brand in order to be alerted to special offers. Friends can also be "defriended" or "unfriended" later on, which may be considered as much of a personal rejection as not returning phone calls.
Unfollow Without Unfriending
Facebook members can "unfollow" their friends, which means that they no longer receive notifications of their posts. They still remain friends however. See Faceslam
and social networking service