Tumors are usually divided into two categories, benign and malignant, according to their growth characteristics and the degree of damage to the human body. Regardless of benign or malignant tumors, they can be classified into epithelial tissue, mesenchymal tissue, neural tissue, lymphopoietic tissue and other tissue tumors according to their tumor tissue origin and tissue type. The classification and naming of tumors are mostly related to their histogenetic origin, biological characteristics, as well as the site and morphological features. Some malignant tumors occur in embryonic cells or immature primitive mother cells, which are then referred to as maternal cell tumors (malignant), such as nephroblastoma and neuroblastoma. If the tumor originated from these tissues is benign, it is called benign nephroblastoma or benign neuroblastoma. Similarly, some benign tumors that originate from multiple tissue components are also called “tumors”, such as mixed tumors and teratomas; if they are malignant, they are also called malignant mixed tumors and malignant teratomas. Malignant tumors occurring in lymphatic tissues are called lymphomas, which can be classified into Hodgkin’s lymphoma (Hodgkin’s disease) and non-Hodgkin’s lymphoma based on the presence or absence of R-S cells in the histocytology. The well-known leukemia is divided into two categories: acute and chronic, which are divided into various types according to the alteration of various blood cells. If classified according to different organs and systems of human body, they can be divided into cranio-cerebral, head and neck, respiratory, circulatory, digestive, urinary, endocrine, reproductive, skeletal, and skin and soft tissue tumors. In conclusion, tumors in various tissues in various parts of human body can be divided into two categories: benign and malignant. Of course, there are some tumors that are between benign and malignant. Although they are benign, their cells are actively proliferating. It is difficult to determine whether they are benign or malignant, so they are called “borderline tumors” or “junctional tumors”.