Arson is the act of intentionally and maliciously setting property, usually buildings, on fire. It is usually done for the purpose of insurance fraud, but can be committed because of addiction to setting things on fire, a condition known as pyromania. Although cases of pyromania are rare, they do happen and you should remember to be careful while judging them as this could be considered a form of mental illness. See Specifications for Warranting a Page/Mental health for information on how to judge these cases.