Cross-country skiing (commonly abbreviated XC skiing) is a winter sport in which participants propel themselves across snow-covered terrain using skis and poles. It is popular in many countries with large snowfields, primarily Northern Europe, Canada, Alaska and the upper midwest United States. Skiing can also be done indoor in ski tunnels.

Cross-country skiing is part of the Nordic skiing sport family, which also includes ski jumping, and a combination sport of cross-country skiing and ski jumping called Nordic combined. Free-technique cross-country skiing is also the method of locomotion in the combination sport of Biathlon, which adds rifle marksmanship to skiing. Another combination sport is ski-orienteering, which adds the skill of map navigation along snow trails and tracks.

Related sports are Backcountry skiing and Telemark skiing. The Ski touring article provides an overview of different ski styles and techniques.