The males of many species in this order are extremely colorful, and iridescent colors are often present. The females have protective coloration. Most species are medium to large in size, with only a few species being small. These birds are predominantly vegetarian ground dwellers with strong feet used for running and scratching for food. They have three toes in front and a shorter one in the back. The males often have spurs which are used for fighting.
Their bills are short and stout. They have strong breast muscles which enable them to fly up quickly. The crop can be distended, and the gizzard is helped in its activity by small pebbles which the bird swallows from time to time. Most species lay many eggs. Incubation is done by the hen alone, the exception being mound building birds, which do not incubate at all. Newly hatched chicks are precocial.
All Gallinaceous birds like to bathe in dust or sand. They are found worldwide except for South America and Antarctica. Their habitats range from desert to rain forests, from sea level to high rocky altitudes over 20,000 feet. Only 4 species migrate, all of them being Quails.