Echinococcus granulosus is a parasitic tapeworm that causes hydatid disease (hydatidosis) in humans. Its life cycle involves carnivores as definitive hosts and herbivores as intermediate hosts. Humans can be infected by ingesting E. granulosus eggs from a definitive host. The larvae develop into hydatid cysts, most commonly in the liver. Hydatid cysts can cause symptoms from pressure or complications like rupture. Diagnosis involves imaging and serology. Treatment depends on cyst type and complications but may include surgery, percutaneous drainage, or antiparasitic drugs.