Teknivals are large free parties which take place for several days. They take place most often in Europe and are often illegal under various national or regional laws. They vary in size from dozens to thousands of people, depending on factors such as accessibility, reputation, weather, and law enforcement. The parties often take place in venues far away from residential areas such as squatted warehouses, empty military bases, beaches, forests or fields. The teknival phenomenon is a grassroots movement which has grown out of the rave, punk, reggae sound system and UK traveller scenes and spawned an entire subculture. Summer is the usual season for teknivals.