Discussion forums: the operating system is the same as that of e-mail, but unlike it, the content is public, since all the people who have access to this forum will be able to see what the other participants have written. In some manuals a forum is defined as an asynchronous textual debate, and it is that true written dialogues can be established between the participants, so that not only can the content of the messages be known, but also one can intervene and contribute something personal .