What types of worms are flat worm?

Flatworms belong to the phylum Platyhelminthes and include several classes, the most notable being Turbellaria (free-living flatworms), Trematoda (flukes), and Cestoda (tapeworms). They are characterized by their flattened bodies and lack of a coelom. Flatworms are typically found in aquatic environments, though some can inhabit terrestrial habitats. They exhibit a range of lifestyles, from free-living predators to parasitic forms.