It’s a tool to share personal short updates (140 characters) with the previously selected users (friends, class mates, community, etc.).
You can only post updates, reply to another user, repeat the publication of another and also mark comment as a favorite.
You will find many more opportunities to interact with the tool: follow, stop following and / or block a user. View activity throughout the Community or see our contacts with our own. See if someone did mention and we responded. See...