Lymph nodes are tissues that are present in the human body from birth, usually in the head and face, neck, supraclavicular fossa or armpit, groin, abdomen, etc. People who are thin or have weak subcutaneous fat can also feel their lymph nodes, but the swelling of lymph nodes is usually caused by two factors, such as viral or bacterial infections in the surrounding tissues and organs, which induce The nearby lymph nodes may become enlarged and painful. In addition, there may be malignant tumors in the tissues and organs near the lymph nodes, and the tumor cells may spread through the lymphatic vessels, affecting the surrounding lymph nodes and causing swelling and pain.