Originally, the Tour de France was sponsored by a sports journal called "l'auto" (the Car), which was printed on yellow paper, now rebranded as the daily "l'équipe" (the Team - still printed on yellow paper). Being the big spender in the event, the newpaper had the idea of dressing the leader of the Tour in the same colour, making him easily recognizable by the spectators.
The yellow jersey
Cycling Tour de France to be specific
Yellow, green, polka dot..?
Tour De france
Greg Lamond
He is the head of the race who everyone follows
A yellow jersey is the yellow-coloured shirt worn by the leader of a cycling race at a certain time during the Tour de France.
Last year's Winner gets to start in the yellow jersey, if he is doing the race.
There is no official purple jersey in the Tour de France. You might have seen a team jersey in that colour.
The famous race that awards the winner of the race the yellow jersey is the Tour de France. The person with the fastest time to the finish is awarded with the honorable yellow jersey.
Canada's Alex Stieda was the first North American to wear the yellow jersey, on Stage 2 of the 1986 Tour de France.
Le Tour de France isn't raced by athletes representing countries, it's raced by professional teams, usually assembled with riders from several different nations. The yellow jersey is worn by the rider with the overall shortest time.