Immunotherapy is a type of biological therapy, which is a type of treatment that uses substances made from living organisms to treat cancer. Several types of immunotherapy are used to treat cancer. These treatments can either help the immune system attack the cancer directly or stimulate the immune system in a more general way. Immunotherapy uses substances made by the body or in a laboratory to improve or restore immune system function. Immunotherapy is used to stop or slow the growth of cancer cells; stops cancer from spreading to other parts of the body; helps the immune system work better at destroying cancer cells. There are several types of immunotherapy which include monoclonal antibodies, non-specific immunotherapy, oncolytic virus therapy, T-cell therapy and cancer vaccines.