Trekking is the preferred word used to describe multi-day hiking in the mountainous regions of India, Pakistan, Nepal, North America, South America, Iran, and the highlands of East Africa. Hiking a long-distance trail from end-to-end is also referred to as trekking and as thru-hiking in some places.
It’s a long, vigorous walk, usually on trails or footpaths in the countryside. Walking for pleasure developed in Europe during the eighteenth century. Religious pilgrimages have existed much longer, but they involve walking long distances for a spiritual purpose associated with specific religions.