A Trek is Not a Climbing Trip
Whether you begin your trek at a road head or fly into a remote mountain airstrip, a large part of it will be in the Middle Hills region at elevations between 500 and 3000 metres. In this region, there are always well-developed trails through villages and across mountain passes. Even at high altitudes there are intermittent settlements used during summer by shepherds, so the trails, though often indistinct, are always there. You can easily travel on any trail without the aid of ropes or mountaineering skills. There are rare occasions when there is snow on the trail, and on some high passes it might be necessary to place a safety line for your companions or porters if there is deep snow. Still, alpine techniques are almost never used on a traditional trek. Anyone who has walked extensively in the mountains has all the skills necessary for an extended trek in Nepal.
Though some treks venture near glaciers, and even cross the foot of them, most treks do not allow the fulfillment of any Himalayan mountaineering ambitions. Nepal's mountaineering regulations allow trekkers to climb 18 specified peaks with a minimum of formality, but you must still make a few advance arrangements for such climbs. Many agents offer so-called climbing treks which include the ascent of one of these peaks as a feature of the trek. There are a few peaks that, under ideal conditions, are within the resources of individual trekkers. A climb can be arranged in Kathmandu if conditions are right, but a climb of one of the more difficult peaks should be planned well in advance.