Bushwalking (also known as rambling, tramping or hiking) is about walking in the Australian bush (area of natural bush and trees which has never been farmed and where there are few people). Bushwalking may involve walking on defined tracks or across-country (off-track) making use of a map and a compass or Global Positioning System (GPS) unit. Walks may be short walks, day walks or multi-day walks where the walker carries all their needs (shelter, food and water) on their back in a backpack.