The three most common gourd types in North America are hardshells, ornamentals and luffas.
Hardshells have woody, rot-resistant shells that can grow to an inch thick under ideal growing conditions. Hardshell gourd tools over a thousand years old have been excavated from sites in Egypt and the Andes of South America. The sturdy hardshell gourd is commonly used for birdhouses, but is also a favorite of pyrographers.
Ornamentals, also known as softshells, are smaller gourds (3-6 inches in diameter) and have thinner shells. The gourd is brightly colored during its growing season, and the ripened vegetable is often used for decoration.
Luffas, also called dishrag gourds, have fibrous interiors that are sometimes used as sponges. The luffa is one of the few types of gourd that is eaten, usually during its immature stage.