Grains are small, hard, dry seeds (with or without attached hulls or fruit layers) harvested for human food or animal feed. Agronomists also call the plants producing such seeds 'grain crops'.

Harvested, dry grains have advantages over other staple foods such as the starchy fruits (e.g., plantains, breadfruit) and roots/tubers (e.g., sweet potatoes, cassava, yams) in the ease of storage, handling, and transport. In particular, these qualities have allowed mechanical harvest, transport by rail or ship, long-term storage in grain silos, large-scale milling or pressing, and industrial agriculture, in general. Thus, major commodity exchanges deal in canola, maize, rice, soybeans, wheat, and other grains but not in tubers, vegetables, or many other crops.