From Social Patterns
When information resources or digital assets are shared directly with a single user or a named group of users, it is referred to as Direct Sharing. While not always a one-to-one relationship (as a user may send the same thing to a list of people), the experience is perceived as direct and point-to-point, as contrasted with Public Sharing which feels more akin to hanging something up in a common space, such as a corkboard in a break room at work, where it may be seen by others who are included in that specific limited public, but in which no single person has been explicitly invited to look.
Direct sharing, however, does imply a direct invitation and may feel more personal. It's important that a social interface have a clear strategy about how to present direct sharing vs. public sharing. If a user is notified or invited to see or do something as if the invitation was personal and direct when in fact it was a blast to a large semi-filtered list of buddies, this can lead to miscommunication and missed opportunities. If Howard Dean really invited me to play a word game with him on Facebook, I'd be flattered and inclined to make some time to do so, but if what really happended is that he (or his intern) accidentally invited everyone on their contact list after installing an application with perhaps a misleading interface, then I am in for a disappointment.
The true common patterns for direct sharing are Send This and Invite to See. The former is analogous to an email message containing a link to a public resource with an optional message, such as "Check out this article I read in USA Today." The latter is similar but involves inviting a person to see one's own posted object or collection, and frequently follows the Public Sharing pattern as a secondary, promotional step.
Also known as Private Sharing.