Sometimes it is hard to tell the difference between a hill and a mountain. Usually a hill does not have steep sides like most mountains. However, a butte is a hill, and it has very steep sides.

Many settlements were originally built on hills, either to avoid floods, or for defense, since they offer a good view of the surrounding land and require would-be attackers to fight uphill. Ancient Rome was built on 7 hills.

Related Terms
butte - a hill with steep sides
dune - a hill of sand
mountain - larger and steeper but like a hill