The lymphatic system is made up of a network of lymph nodes and vessels or channels throughout the body. This system carries lymph fluid, nutrients, and waste material between the body tissues and the bloodstream.

The lymphatic system is also an important part of the immune system, the body's defense 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.

When a part of the body is infected, the nearby lymph nodes become swollen as they collect and destroy the infecting organisms. For example, if a person has a throat infection, lymph nodes in the neck may swell and become tender.

Cancer can spread through the lymphatic system.