The Blue Riband (pronunciation: /ˌbluː ˈrɪbənd/) is an unofficial accolade given to the passenger liner crossing the Atlantic Ocean westbound in regular service with the record highest speed. The term was borrowed from horse racing and was not widely used until after 1910. Under the unwritten rules, the record is based on average speed rather than passage time because ships follow different routes. Traditionally, a ship is considered a "record breaker" if it wins the eastbound speed record, but is not credited with the Blue Riband unless it wins the more difficult westbound record against the Gulf Stream.