Nematodes are a diverse group of roundworms that are found in a wide range of habitats including soil, water, plants, and animals. They are one of the most diverse and abundant groups of animals on Earth, with an estimated 1 million species. Nematodes play important roles in ecosystems by cycling nutrients, controlling pest populations, and serving as food sources for other organisms. They are also important in agriculture as both beneficial organisms and destructive pests. Researchers study nematodes to better understand their biology, ecology, and interactions with other organisms in order to develop more sustainable agricultural practices, control parasitic infections in humans and animals, and preserve biodiversity.