Parasitism is a type of symbiotic relationship where one organism, called the parasite, benefits at the expense of another organism, known as the host. The parasite relies on the host for nutrients and shelter, often harming the host in the process. Common examples of parasites include tapeworms, fleas, and lice. In parasitism, the host may experience various negative effects, such as weakened health or reduced reproductive success. While some parasites can cause diseases in their hosts, others may have less severe impacts. Understanding parasitism is important in fields like ecology and medicine, as it helps in managing health and environmental issues.