Every time a new ship is built, the shipyard in question must provide proof that the ship can withstand stresses involving, for example, swell, weather or cargo. With a view to protecting the environment, documentation regarding the use of hazardous materials and the emission of pollutants during operation has also been required in recent years. Verifying all this is a task performed by classification societies. Only when a vessel has been assigned a certain ship class, e.g. for a region or certain purpose, can the shipping company involved obtain insurance for the ship and is allowed to call at ports or travel through sea areas.