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

In the United Kingdom, hiking is a slightly old-fashioned word, with a flavour rather of 'heartiness' and 'exercise' than of 'enjoying the outdoors' (people in the UK would be more likely to use more modest terms such as hillwalking, or simply walking). Australians use the term bushwalking for both on- and off-trail hiking. New Zealanders use tramping (particularly for overnight and longer trips), walking or bushwalking. Hiking in the mountainous regions of Nepal and India is sometimes called trekking. Overnight hiking is called backpacking in some parts of the world. Hiking a long-distance trail from end to end is referred to as thru-hiking in some places.

Hiking is one of the fundamental outdoor activities on which many others are based. Many beautiful places can only be reached overland by hiking. Enthusiasts regard hiking as the best way to see nature. It is seen as better than a tour in a vehicle of any kind (or on an animal; see horseback riding) because the hiker's senses are not intruded upon by distractions such as windows, engine noise, airborne dust in large quantities, and fellow passengers. It has an advantage over standing in one place because the hiker may cover a wide area.

Hiking is a recreational experience. As such, hikers expect it to be pleasant. Sometimes hikers can interfere with each others' enjoyment, or the enjoyment of other users of the land. Such interference can be minimized by hikers who follow good etiquette. Examples of such interference and etiquette include:

• When two groups of hikers meet on a steep trail, there may be contention for use of the trail. To avoid conflict, a custom has developed: the group moving uphill has the right-of-way. In other situations the larger of the two groups will yield to the smaller.

Hiking in a group increases safety, but hikers may wish to hike at different rates.

• Being forced to hike much faster or slower than one's natural pace can be annoying, and difficult to maintain consistently. More seriously, walking unnaturally fast causes dramatically increased fatigue and exhaustion, and may result in injury. If a group splits between fast and slow hikers, the slow hikers may be left behind or become lost. A common custom is to encourage the slowest hiker to hike in the lead and have everyone match that speed. Another custom is to have an experienced hiker sweep up the rear, to ensure that everyone in the group is safe and nobody straggles.
• Hikers often enjoy the silence and solitude of their surroundings. This enjoyment is disrupted by loud sounds, such as shouting or loud conversation. Some hikers purposely avoid loud sounds, out of deference to other hikers. Staying quiet will also increase the likelihood of encountering wildlife. (This is a hazard if dangerous animals are present; see "Personal safety hazards".)