Mountaineering is the sport and skill of climbing mountains, especially high or difficult ones. A mountaineer might spend days ascending a peak like Mount Rainier or Mount Everest, carrying equipment, setting up camps at different elevations, and using ropes, ice axes, and crampons (metal spikes attached to boots) to navigate steep rock faces and frozen slopes.

Mountaineering combines physical endurance with technical skills and careful planning. Mountaineers must understand weather patterns, know how to prevent altitude sickness, and work as a team to stay safe in environments where mistakes can be deadly. They often climb in rope teams, where climbers tie themselves together so if one person slips, the others can stop the fall.

Famous mountaineers like Edmund Hillary and Tenzing Norgay, who first reached Everest's summit in 1953, spent years learning their craft before attempting such dangerous climbs.

While some people use mountaineering and rock climbing interchangeably, mountaineering specifically involves ascending tall mountains and dealing with challenges like thin air, extreme cold, and glaciers. Rock climbing typically focuses on climbing rock faces at lower elevations, where altitude and weather extremes are less of a factor.