Dog racing, also called greyhound racing, is a sport in which greyhounds compete on an oval track. The dogs chase a mechanical lure that may resemble a bone, another greyhound, or a rabbit. Sometimes a wind sock is used. A mechanical lure is effective because greyhounds chase by sight rather than by scent. The lure moves around the track on an electric rail. Greyhound racing developed from coursing, an ancient sport in which two dogs chased a live rabbit over an open field.