An accident is an event of fortuitous nature. it can harm the integrity of persons, material goods, or environment. An accident can be minor or major, in the first case it is called an incident, if it is very serious it can be defined as a disaster.

Road accidents are among the most common, transport is moreover a field where accidents are often serious, particularly massive transports like plane or train. Sometimes it is the transported good which contains the risk (oil, chemicals...) and can provoke accidents such as oil spills.

Most of the time, accidents lead to the elaboration of rules, laws, protection and prevention measures, the shock caused by the consequences of the accident often leads to reaction.

Men themselves are often straightly responsible for an accident, but in some cases machines, tools or transport ways used are subject to fault. Nuclear accidents like the Tchernobyl one in Ukraine in 1986 makes part of this category.

Most serious accidents, that is to say disasters, are caused by the nature. Tsunamis, earthquakes, inundations, cyclones, hurricanes, all these major natural phenomena usually have tremendous consequences on both human and material goods. Natural phenomena is often amplified by man's action.