In many sports, a competition number is used to identify and differentiate the competitors taking part in a competitive endeavour. For example, runners in a race may wear prominent competition numbers so that they may be clearly identified from a distance. Competition numbers are differentiated from uniform numbers in that the former are used for a specific event (for example, competition numbers worn by marathon runners) while the latter persist over time through multiple events, seasons, or sometimes an entire career (for example, uniform numbers worn by Major League Baseball players).