A rampart is, in other words, a castle wall. A parapet is a less defensive wall, such as a fence. A battlement is a defensive stone parapet on top of a rampart with crossbow grooves and apertures. A battlement and a crenellation are the same thing. A moat is a trench filled with water that surrounds most castles and fortresses. Ramparts and battlements were originally used for defense. Today they are popular additions to homes, hotels, and restaurants because of their aesthetic value. They can also be used to enhance security by preventing people from climbing over or into them. The word "rampart" comes from French "randon", which means "wide". The term "rampart defense" was first used by Francis Bacon in his 1627 book New Atlantis. He wrote that a country could protect itself against invasion by building walls around cities or villages. But since an army would need food and rest, those walls would have to be very high to prevent attacks by gunpowder weapons. This type of defense was not practical for countries without much land or money. Bacon also proposed that instead of using powder, armies should fight by hitting arrows into the ground next to the enemy's wall. When an attacker's arrow hits a pebble on the rampart, it kills him. This is how towns with ramparts protected themselves from attack.