Land surfaces characterized by roughness and strong relief. The distinction between hills and mountains is usually one of relative size or height, but the terms are loosely and inconsistently used. Because of the prevalence of steep slopes, hill and mountain lands offer many difficulties to human occupancy. Cultivable land is scarce and patchy, and transportation routes are often difficult to construct and maintain. However, many rough lands, especially those readily accessible to centers of population, attract tourists because of their scenic quality and the opportunities they may afford for outdoor recreation.