Roundworms, scientifically known as Nematoda, are a diverse group of elongated, cylindrical worms found in various environments, including soil, freshwater, and marine habitats. They play essential roles in ecosystems, such as decomposing organic matter and serving as food for other organisms. These worms can be free-living or parasitic, with some species affecting plants and animals, including humans. Parasitic roundworms, like Ascaris lumbricoides, can cause significant health issues, making them a concern in public health. Understanding roundworms is crucial for both ecological balance and human health.