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 while the latter persist over time through multiple events, seasons, or sometimes an entire career.

Kathrine Virginia Switzer is an American marathon runner, author, and television commentator.