Immunotherapy involves activating or suppressing the immune system to fight diseases like cancer. There are two main types - activation immunotherapies that elicit an immune response and suppression immunotherapies that reduce it. Methods include monoclonal antibodies, cancer vaccines, cytokines, and immunomodulators that control immune response levels. The goal is to stimulate the immune system to attack tumor cells through approaches like naked or conjugated monoclonal antibodies, cancer vaccines, and nonspecific therapies including cytokines and interleukins.