Macaca fascicularis, commonly known as the long-tailed macaque or crab-eating macaque, is a species of primate found in Southeast Asia. They inhabit a variety of environments, including forests, mangroves, and urban areas. These monkeys are known for their adaptability and social behavior, often living in large troops. Long-tailed macaques have a distinctive long tail that helps them balance while climbing. They are omnivorous, feeding on fruits, seeds, and small animals. Their intelligence and ability to use tools make them a subject of interest in animal behavior studies.