A casquette (from French 'cap') is a peaked cotton cap traditionally worn by road cyclists.
[1] With the introduction of compulsory cycle helmets for massed-start racing, casquettes have become less common, but most professional race outfits still have them produced in team colours for wearing on the winners' podium, for wearing under a helmet in heavy rain or for sale to the tifosi.
They have also become popular as fashion items in some European, American and Australian cities, often with non-cycling-related designs.
The casquette shields the head from strong sun and the peak can also make riding in the rain more comfortable, since drops do not fall directly into the eyes.
Some varieties also incorporate a sweatband to help prevent sweat from dripping into the eyes.