Baseball caps are made of many types of material and shaped in various styles for different purposes. Major and minor league baseball players wear classic-style caps made of wool (or, more recently, polyester) with their team's simple logo and colors; the logo is usually embroidered into the fabric.
Formerly, baseball caps only came in standard hat sizes. Since 1980, they have also been available in a one-size-fits-all form, with an adjustment strap in the back. The style, commonly called snapback, has become increasingly popular as fashion accessories.
Advances in textiles have led to the "stretch-fit" hat, which uses Lycra or rubber to allow a hat to have a fitted style while still being "adjustable" within sizes.
Another version of the baseball cap is a plastic mesh cap with a foam front imprinted with a company logo. This style of baseball cap is sometimes called a trucker cap or a "gimme cap" because it is given away for free as a promotional item.