The system of the award has changed during the years. Historically, riders accumulated points, but the current system awards prizes on each stage except for time trials. There is also an award for the most combative rider of whole Tour. The rider has to finish the race in order to win the award.
There isn't a jersey for most combative rider, but instead, it is marked with a white number on a red background instead of the usual black on white. The award is sponsored by Brandt.