A gizzard is a muscular part of the digestive system found in birds, reptiles, and some fish. It helps grind up food, especially hard materials like seeds and grains, which the animal cannot chew. The gizzard works in conjunction with the crop, where food is initially stored, and the stomach, where digestion begins. In birds, the gizzard often contains small stones or grit that aid in the grinding process. This adaptation allows these animals to efficiently break down tough food items, making nutrients more accessible for absorption in the intestines. The gizzard is an essential component of the digestive system for many species.