A milestone is a numbered marker placed on a route such as a road, railway line, canal or boundary. They can indicate the distance to towns, cities, and other places or landmarks; or they can give their position on the route relative to some datum location. On roads they are typically located at the side or in a median or central reservation. They are alternatively known as mile markers, mileposts or mile posts (sometimes abbreviated MPs). Commonly the term "milestone" may also refer to markers placed at other distances, such as every kilometre.