The forum activity allows students and teachers to exchange ideas by posting comments as part of a 'thread'. Files such as images and media maybe included in forum posts. The teacher can choose to grade and/or rate forum posts and it is also possible to give students permission to rate each others' posts.
To add a forum you should turn on the editing and select it from the Activity chooser.
Which forum do I need?
In the (default) Standard forum for general use, students will see an introduction text in a separate space above the list of discussions. Students see a button to start a new discussion (thread).
In a Single, simple discussion the teachers posts a question and students are able only to reply. They cannot start a new topic of discussion. This is useful if you wish to keep a discussion focused.
The Question and Answer forum is best used when you have a particular question that you wish to have answered. The teacher posts a question and students respond with possible answers. By default a Q and A forum requires students to post once before viewing other students' postings.
The Standard forum displayed in a blog-like format works like the standard forum for general use, but the first post of each discussion is displayed (as in a blog) so that users can read it and then choose to respond by clicking the "Discuss this topic" button bottom right of the post.