World championships were first held in 1893, in Chicago, under the ICA. They were for amateurs. Separate professional races were held from 1895, in Cologne. Amateurs and professionals competed in separate events until 1993, after which they raced together in "open" races. Championships are open to riders selected by their national cycling association. They compete in the colours of their country.
The winner of ICA championships received a gold medal. The UCI awards a gold medal and a rainbow jersey to the winner. Silver and bronze medals are awarded to the second and third place contestants. World champions wear their rainbow jersey until the following year's championship, but they may wear it only in the type of event in which they won it. Former champions can wear rainbow cuffs to their everyday jerseys.
World track championships are allocated to different countries each year. They are run by that country's national cycling association, although the judges are provided by the UCI.