The basic baseball cap is a soft cap with a curved or flat stiff brim. The cap is adjusted to fit heads of various sizes by tightening or loosening a strap on the back of the cap. The adjuster is often made of plastic, Velcro, elastic or cloth with a metal buckle.

Baseball caps are traditionally worn by american baseball players. Today the baseball cap is often worn as a fashion accessory. Baseball caps are most popular in the countries of Brazil, Japan and the United States.