Forum - The forum is the whole installation, and usually contains multiple boards.

Board - A board contains topics, which in turn contain the posts.

Topic - A topic, otherwise known as thread, contains all the posts on a specific subtopic in threaded form, displayed by indentation. Each topic has a subject.

Post - A post is a single public message by a user. It can be either a first post, which starts a new topic, or a reply to an existing topic.

User - user is anyone who writes posts in the forum.

Forum Administrator - - A forum admin can control and edit everything in the forum. A forum can have multiple forum admins.