Rodents are mammals belonging to the order Rodentia, characterized primarily by a single pair of continuously growing incisors in both their upper and lower jaws, which they use for gnawing

. They make up about 40% of all mammal species, with over 2,000 species worldwide, making them the largest group of mammals

. Rodents are found on every continent except Antarctica and some isolated islands, and they inhabit diverse environments ranging from forests and grasslands to urban areas

. They exhibit varied lifestyles, including arboreal (tree-dwelling), fossorial (burrowing), saltatorial (leaping), and semiaquatic habits

. Common examples of rodents include mice, rats, squirrels, porcupines, beavers, guinea pigs, hamsters, prairie dogs, and capybaras

. They vary greatly in size, from tiny pygmy jerboas weighing a few grams to large capybaras weighing around 50 kilograms

. Rodents are known for their sharp, ever-growing incisors that require constant gnawing to keep them from overgrowing

. Their diets are mostly herbivorous, but some species are omnivorous or even predatory

. Many rodents are social and communicate in complex ways, and their reproductive strategies vary widely

. Some rodents, especially species like the brown rat, black rat, and house mouse, are considered pests because they can damage property, contaminate food, and spread diseases to humans and animals

. Rodents have also been important to humans as pets, food sources, and laboratory animals for research

. In summary, rodents are a diverse and widespread group of gnawing mammals distinguished by their unique dental structure and adaptability to many habitats worldwide