A moderated forum refers to an online forum for discussion in which all posts are pre-approved by a moderator before being posted for the group. Some people prefer a this type of forum to an unmoderated one, as the moderator can not only keep outspam, but posts that are inappropriate, rude or offensive, or that wander off topic.
The Internet has always been known for its unmoderated, uncensored landscape. No one “owns” the Internet, and no policing service is responsible for controlling it. Instead it is built foremostly on voluntary cooperation both at the network level, and at the level of social interaction. To this end most social forums on the Internet have a set of rules or protocols members are requested to follow.
Though the idea of voluntary cooperation is idealistically appealing to responsible persons worldwide and has been a great success, its strength is also its weakness. Irresponsible people can use unmoderated forums for their own purposes to harass, harangue and otherwise foil a forum’s charter, at least temporarily, by choosing to ignore netiquette. In most cases trolls like this can be ignored and they will eventually move on, but there are situations in which a moderated forum is more productive.
A support group is a prime example of good use of a moderated forum. People who are seeking help from others who might be suffering from illnesses or trying circumstances are spared distractions by having a moderator filter posts to the group. The moderator’s job is not to pass judgment on legitimate replies or posts to the group, but simply to keep out posts that are at odds with the forum’s ground rules.
Though the example above is a particularly relevant one, there are many forums dedicated to more idle subjects that are also moderated. This is especially true now that Web forums have become commonplace, routinely offered by website host providers to anyone who can point-and-click. This type of moderated forum is commonly more select and the domain owner typically acts as moderator to his or her own chat forum.
Other types of forums fall somewhere in the middle. Media websites such as news outlets or sites dedicated to particular television shows might allow all posts through with a moderator reading them after the fact, perhaps within 48 hours. Offensive posts are then removed. In some cases a moderator might not read posts at all unless someone complains. Another exercised option to run a moderated forum is to use filtering software that pulls posts which contain swear words or other objectionable content.
Source: WiseGeek