Maillot Jaune

The leader's jersey since 1919, first worn by Eugène Christophe on the road to Geneva.

via Wikipedia: General classification in the Tour de France · see source

The maillot jaune, or yellow jersey, is worn by the leader of the Tour de France general classification, the race's most important ranking. The first two Tours were decided on cumulative time and their leader wore a green armband rather than a jersey; from 1905 the classification was decided on points, and it returned to time after 1912. According to the official history the first yellow jersey was worn by Eugène Christophe on the stage from Grenoble to Geneva on 19 July 1919; he disliked it and complained that spectators imitated canaries as he passed.

The Belgian Philippe Thys, winner in 1913, 1914 and 1920, later recalled being asked by Henri Desgrange to wear a coloured jersey as early as 1913, first refusing and then giving in at the urging of his Peugeot team manager Alphonse Baugé, so the jersey's true origin remains uncertain. The French bank Crédit Lyonnais has sponsored the jersey since 1987, under the LCL name from 2007.