hello, thank you for asking this question. Lymph nodes are small, bean-shaped glands throughout the body. They are part of the lymphatic system, which carries fluid (lymph fluid), nutrients, and waste material between the body tissues and the bloodstream. The lymphatic system is an important part of the immune system, the body s defense system against disease. The lymph nodes filter lymph fluid as it flows through them, trapping bacteria, viruses, and other foreign substances, which are then destroyed by special white blood cells called lymphocytes. Lymph nodes may be found singly or in groups. And they may be as small as the head of a pin or as large as an olive. Groups of lymph nodes can be felt in the neck, groin, and underarms. Lymph nodes generally are not tender or painful. Most lymph nodes in the body cannot be felt. When lymph nodes swell in two or more areas of the body, it is called generalized lymphadenopathy. This may be caused by: A viral illness, such as measles, rubella, chickenpox (varicella), or mumps. Mononucleosis (Epstein-Barr virus), which results in fever, sore throat, and fatigue, or cytomegalovirus (CMV), a viral infection that causes symptoms similar to those of mononucleosis. A bacterial illness, such as strep throat (caused by the streptococcus bacterium) or Lyme disease (a bacterial infection spread by certain types of ticks). Side effects of phenytoin (Dilantin), a medicine used to prevent seizures. Side effects of measles-mumps-rubella (MMR) vaccination. Cancer, such as leukemia, Hodgkin s disease, and non-Hodgkin s lymphoma. Acquired immunodeficiency syndrome (AIDS), which develops after contracting HIV (human immunodeficiency virus). This virus attacks the immune system, making it difficult for the body to fight off infection and some disease. Syphilis, a sexually transmitted disease. Kind regards