Synchronous interaction requires all participants to be online at the same moment in time.
Users who log off or otherwise lose their connection to the conversation can't recapture dialog that unfolds in their absence, unless a transcript is kept and posted online for later retrieval. Participants can reach people half a world away for the price of the local call that connects them with the Internet . Groups of individuals can convene for meetings and discussions. With the proper software, it's even possible to display and work on documents and diagrams together, while you talk. It isn't always a good experience for users who must connect via slow dial up .