Message Boards
Message boards are also sometimes called web based discussion forums. Users can interact not only across space, but across time as well. Messages are stored over a period of time, and can be responded to at the leisure of the discussion's participants. Although Web forums update their messages in real-time, because of the relative "permanence" of the posts, other users aren't required to be standing nearby to read or respond (as in a chat room).

Chat Rooms
Chat rooms are probably the most famous discussion medium on the Net. Their function is quite simple: they allow multiple users to log into a real-time interface and exchange words and sentences.

The big advantage of chat over other discussion media is its ability to simulate live discussion. Chat rooms, in order to be effective, needs a significant amount of traffic on a web site at the same time. For smaller web sites / communities, chat rooms should be either reserved for special planned events only or consideration should be given to using message boards.