Cancer, one of the leading causes of death worldwide has several therapeutic methods such as surgery, chemotherapy and radiotherapy. Novel strategies like immunotherapy have gained importance in the recent decades. The main principles of cancer immunotherapy include targeting the tumor directly with the help of or/and activating the immune cells to improve immune response. These immunotherapies fall into 6 main classes, including checkpoint inhibitors, lymphocyte-activating cytokines, CAR T cells and other cellular therapies, agonistic antibodies against co-stimulatory receptors, monoclonal Abs against TAs and cancer vaccines. Their mechanism of action and efficacy against different tumors are discussed in detail in this paper