A forum consists of a tree like directory structure. The top end is "Categories". A forum can be divided into categories for the relevant discussions. Under the categories are sub-forums and these sub-forums can further have more sub-forums. The topics (commonly called threads) come under the lowest level of sub-forums and these are the places under which members can start their discussions or posts. Logically forums are organized into a finite set of generic topics (usually with one main topic) driven and updated by a group known as members, and governed by a group known as moderators. It can also have a graph structure. All message boards will use one of three possible display formats. Each of the three basic message board display formats: Non-Threaded/Semi-Threaded/Fully Threaded, has its own advantages and disadvantages. If messages are not related to one another at all a Non-Threaded format is best. If a user has a message topic and multiple replies to that message topic a semi-threaded format is best. If a user has a message topic and replies to that message topic, and replies to replies, then a fully threaded format is best.
Internally, Western-style forums organize visitors and logged in members into user groups. Privileges and rights are given based on these groups. A user of the forum can automatically be promoted to a more privileged user group based on criteria set by the administrator.A person viewing a closed thread as a member will see a box saying he does not have the right to submit messages there, but a moderator will likely see the same box granting him access to more than just posting messages.
An unregistered user of the site is commonly known as a guest or visitor. Guests are typically granted access to all functions that do not require database alterations or breach privacy. A guest can usually view the contents of the forum or use such features as read marking, but occasionally an administrator will disallow visitors to read their forum as an incentive to become a registered member. A person who is a very frequent visitor of the forum, a section or even a thread is referred to as a lurker and the habit is referred to as lurking. Registered members often will refer to themselves as lurking in a particular location, which is to say they have no intention of participating in that section but enjoy reading the contributions to it.
The moderators (short singular form: "mod") are users (or employees) of the forum who are granted access to the posts and threads of all members for the purpose of moderating discussion (similar to arbitration) and also keeping the forum clean (neutralizing spam and spambots etc.). Moderators also answer users' concerns about the forum, general questions, as well as respond to specific complaints. Common privileges of moderators include: deleting, merging, moving, and splitting of posts and threads, locking, renaming, stickying of threads, banning, suspending, unsuspending, unbanning, warning the members, or adding, editing, removing the polls of threads. "Junior Modding", "Backseat Modding", or "Forum copping" can refer negatively to the behavior of ordinary users who take a moderator-like tone in criticizing other members.
Essentially, it is the duty of the moderator to manage the day-to-day affairs of a forum or board as it applies to the stream of user contributions and interactions. The relative effectiveness of this user management directly impacts the quality of a forum in general, its appeal, and its usefulness as a community of interrelated users.
The administrators (short form: "admin") manage the technical details required for running the site. As such, they may promote (and demote) members to/from moderators, manage the rules, create sections and sub-sections, as well as perform any database operations (database backup etc.). Administrators often also act as moderators. Administrators may also make forum-wide announcements, or change the appearance (known as the skin) of a forum. There are also many forums where administrators share their knowledge.
A post is a user-submitted message enclosed into a block containing the user's details and the date and time it was submitted. Members are usually allowed to edit or delete their own posts. Posts are contained in threads, where they appear as blocks one after another. The first post starts the thread; this may be called the TS (thread starter) or OP (original post). Posts that follow in the thread are meant to continue discussion about that post, or respond to other replies; it is not uncommon for discussions to be derailed.
On Western forums, the classic way to show a member's own details (such as name and avatar) has been on the left side of the post, in a narrow column of fixed width, with the post controls located on the right, at the bottom of the main body, above the signature block. In more recent forum software implementations, the Asian style of displaying the members' details above the post has been copied.
Posts have an internal limit usually measured in characters. Often one is required to have a message of minimum length of 10 characters. There is always an upper limit but it is rarely reached – most boards have it at either 10,000, 20,000, 30,000, or 50,000 characters.
Most forums keep track of a user's postcount. The postcount is a measurement of how many posts a certain user has made. Users with higher postcounts are often considered more reputable than users with lower postcounts, but not always. For instance some forums have disabled postcounts with the hopes that doing so will emphasize the quality of information over quantity.
A thread (sometimes called a topic) is a collection of posts, usually displayed from oldest to latest, although this is typically configurable: Options for newest to oldest and for a threaded view (a tree-like view applying logical reply structure before chronological order) can be available. A thread is defined by a title, an additional description that may summarize the intended discussion, and an opening or original post (common abbreviation OP, which can also mean original poster), which opens whatever dialogue or makes whatever announcement the poster wished. A thread can contain any number of posts, including multiple posts from the same members, even if they are one after the other.
A thread is contained in a forum, and may have an associated date that is taken as the date of the last post (options to order threads by other criteria are generally available). When a member posts in a thread it will jump to the top since it is the latest updated thread. Similarly, other threads will jump in front of it when they receive posts. When a member posts in a thread for no reason but to have it go to the top, it is referred to as a bump or bumping. It has been suggested that "bump" is an acronym of "bring up my post"; however, this is almost certainly a backronym and the usage is entirely consistent with the verb "bump" which means "to knock to a new position".
On some messageboards, users can choose to sage (correctly pronounced /sa-ɣe/ though often confused as IPA: [seɪdʒ]) a post if they wish to make a post, but not "bump" it. The word "sage" derives from the 2channel terminology 下げる sageru, meaning "to lower".
Threads that are important but rarely receive posts are stickyed (or, in some software, "pinned"). A sticky thread will always appear in front of normal threads, often in its own section. A "threaded discussion group" is simply any group of individuals who use a forum for threaded, or asynchronous, discussion purposes. The group may or may not be the only users of the forum.
A thread's popularity is measured on forums in reply (total posts minus one, the opening post, in most default forum settings) counts. Some forums also track page views. Threads meeting a set number of posts or a set number of views may receive a designation such as "hot thread" and be displayed with a different icon compared to other threads. This icon may stand out more to emphasize the thread. If the forum's users have lost interest in a particular thread, it becomes a dead thread.