An Internet forum, or message board, is an online discussion site for user-generated content. Most forums are centered around a particular topic or community. Forums provide an easy, efficient way for a community to come together on a particular content area.
Web-based forums are powered by software and can be integrated into an existing web site or can be accessed as an external service to a web site. Various forum software offer different features, from the most basic, providing text-only postings, to more advanced packages, offering multimedia support and formatting code (usually known as BBCode). Forum software may also allow direct communication between subscribers via e-mail or direct message (DM).
Forums typically are structured into categories, forums, threads, and posts. Categories are areas of discussion ("Cameras", for example). Forums are a particular area of more specific discussion ("Nikon DSLRs", for example). Threads are a particular discussion topic that are initiated by a unique post to a forum ("Best 10mm lens?"). And posts are individual messages posted to a particular thread. Posts can single-threaded (linear posts where you reply to the first post or to any previous post, such as what you'd typically see at the bottom of a blog posting) or multi-threaded (hierarchically presented posts where you can reply to specific posts).
Forum administrators can allow anonymous posting to forums or can require any level of registration and/or authentication. Because of the likelihood of spam, most forums require registration at a minimum. Forums are governed by a set of individuals, collectively referred to as staff, made up of administrators and moderators, which are responsible for the forums' conception, technical maintenance, and policies (creation and enforcing). Most forums have a list of rules detailing the wishes, aim and guidelines of the forums creators. The rules can be very stringent or very relaxed. In general, the rules of a forum should allow expression and creativity, while also maintaining civility and conversation on the topics at hand. The term "Troll" is commonly used to describe someone who posts inflammatory comments on forums to "stir the pot" or cause confrontation. Such posts often result in "flame wars", or a series of personal, attacking, back-and-forth postings.
There are hundreds of distinct forum software programs. phpBB and Vbulletin are some of the most commun. PunBB is an increasingly popular forum software that provides high levels of accessibility.