The activity also attracts tourists from overseas and is important to the economy in rural areas.
Routes on established trails are usually well marked and cover a huge variety of landscapes and terrain from mountains, moorlands, lochs and forests, to islands, coasts, rivers and historical sites.
Lochs and mountain trails include the Great Glen Way, in the Highlands, the Southern Upland Way, Britain's first coast to coast route in southern Scotland, and the Three Lochs Way, which links Loch Lomond, The Gareloch and Loch Long. The Speyside Way follows the River Spey from Aviemore in the Cairngorms to Spey Bay in the Moray Firth.
For the committed rambler Scotland's 282 munros - mountains over 3000 feet - provide a special challenge. More than 4000 walkers have bagged all of the munros, an achievement which was first completed by Hamish Brown in 1974.
A study of the new John Muir Way has estimated the route will create or safeguard 130 jobs in the first 12 months, rising to more than 1000 jobs in five years and inject £42 million into the economy.