These words are near synonyms. The cereals (from Ceres, the Roman goddess of agriculture) are plants in the grass family, the Gramineae, whose members produce edible and nutritious seeds, the grains. But cereal is also used to mean their seeds and products made from them—as in “breakfast cereals”—and the plants are sometimes called grains. The cereals and other grasses are creatures of the open plain or high-altitude steppe, areas too dry for trees. They live and die in a season or two, and are easily gathered and handled. They grow in densely packed stands that crowd out competition, and produce many small seeds, relying on numbers rather than chemical defenses to ensure that some offspring will survive. These characteristics made the grasses ideal for agriculture. With our help, they have come to cover vast areas of the globe.