From Social Patterns
Flame wars break out when a person responds in a volatile manner to a negative, hostile or otherwise personal attack against them by another person (usually a troll – a person trolling for a reaction). These usually happen in forums or message lists but can also take place in online chats, in IM and in comments on an object.
A flamer often starts out espousing an opinion as the only valid opinion on the topic being discussed. The conversation then devolves as others challenge that opinion and the flamer begins making personal attacks.
In most social contexts, flame wars are not welcome and are against the terms of service. The flame war hijacks the conversation away from the majority. In many cases the flame war will die down as the community moderates itself and makes it clear that this kind of behavior is not tolerated. In more extreme cases, a community moderator, site owner or those who uphold a company’s terms of service have to be brought in to address the situation. Community moderation can cut a flame war off at the knees by censuring the participants or throwing the participants off the service.