A classification yard (American and Canadian English) or marshalling yard (British, Hong Kong, Indian and Canadian English) is a railway yard found at some freight train stations, used to separate railway cars on to one of several tracks. First the cars are taken to a track, sometimes called a lead or a drill. From there the cars are sent through a series of switches called a ladder onto the classification tracks. Larger yards tend to put the lead on an artificially built hill called a hump to use the force of gravity to propel the cars through the ladder.