Trematodes, commonly known as flukes, are a type of parasitic worm belonging to the class Trematoda. They typically have flat, leaf-shaped bodies and can live in various hosts, including humans, animals, and fish. These organisms often inhabit the liver, lungs, or intestines of their hosts, where they can cause various health issues. Life cycles of trematodes are complex, usually involving multiple hosts. They often start as eggs that hatch into larvae, which then infect intermediate hosts like snails. Eventually, they mature into adult flukes in their final host, where they can reproduce and continue their life cycle, sometimes leading to diseases such as schistosomiasis.