Trekking is an activity that forms part of the increasing adventure and outdoor tourism. High altitude trekking has been popular for some time. For longer treks, porters are employed to carry necessary equipment. The word trek has entered the English language as one of few words derived from Afrikaans. It means a long, hard journey, and is derived from the Middle Dutch trecken (meaning to pull or haul). Hiking is often called Trekking , especially in mountainous regions.

Hiking is a form of walking, undertaken with the specific purpose of exploring and enjoying the scenery. It usually takes place on trails in areas of relatively unspoiled wilderness.

Off-trail hiking is often called 'bushwalking', 'bushwhacking', 'bush-bashing' or 'cross country hiking'. Overnight hiking is more specifically called 'backpacking'. The word 'hiking' is understood in all English-speaking countries, but regional terms also exist. In the United Kingdom, the activity is often simply called 'walking'. Australians use the term bushwalking for both on- and off-trail hiking. New Zealanders commonly employ the word tramping, particularly for overnight trips. Hiking in the mountainous regions of Nepal and India is sometimes called 'trekking'.

Hiking is one of the fundamental outdoor activities on which many others are based. Hiking is the only way to reach many beautiful places overland. Enthusiasts regard hiking as the best way to see nature.