A mountain is an elevated portion of the surface of a planet, generally with steep sides that show significant exposed bedrock. Although there are no universally accepted definitions, a mountain is usually considered higher than a hill. By definition, mountains are often thought of as being a landform which is higher than 2,000 feet (610 m). It may either have a limited summit area or be a smaller plateau with high elevation and steep sides. A few mountains are isolated summits, but most occur in mountain ranges.