The Order Rodentia is the largest order of mammals, encompassing over 2,200 species, including mice, rats, squirrels, beavers, porcupines, and guinea pigs. Rodents are characterized by a single pair of continuously growing incisors in each jaw, which they use for gnawing wood, seeds, and other materials. They are found worldwide in nearly every habitat, from forests and grasslands to urban areas. Rodents display diverse diets, mostly herbivorous but sometimes omnivorous, and are known for their high reproductive rates. Ecologically, they play important roles as seed dispersers, prey for predators, and ecosystem engineers, though some species are also significant agricultural pests or vectors of disease.