Forum

An Internet Forum, is an online discussion site where people can hold conversations in the form of posted messages. They differ from Chat rooms in that messages are at least temporarily archived. So asynchronous interaction is possible. Also, depending on the access level of a user or the forum set-up, a posted message might need to be approved by a moderator before it becomes visible. A discussion forum is hierarchical or tree-like in structure: a forum can contain a number of subforums, each of which may have several topics. Within a forum's topic, each new discussion started is called a thread, and can be replied to by as many people as wish to. Depending on the forum's settings, users can be anonymous or have to register with the forum and then subsequently log in in order to post messages. On most forums, users do not have to log in to read existing messages.

In educational settings a Forums can always be used, when discussions are to take place. As it is a typical asynchronous tool sufficient time should be planned for the discussion to take place. 

Usually any learning-platform will have its own Forum, but there are also websites providing the possibility to create your own free forums like http://www.freeforums.org/ (Ad-Free).