Lymphatic drainage massage is a specific type of massage in which lymph drainage through the body is increased.
Many people are familiar with the circulatory system, which moves blood around the body, but they may not be as familiar with the lymphatic system, because it isn't quite as flashy. However, this system is still extremely important, as lymph performs a number of vital functions in the body, especially in the context of the immune system. You have probably seen your own lymph; if a cut has ever oozed a clear fluid, that was lymph.
Lymph generates several types of cells which are important to the immune system, and it also traps substances which the body identifies as dangerous. It also plays a role in the transport of fatty acids and other substances, helping the digestive tract process food more efficiently. As lymph circulates, passing through the lymph nodes, it becomes more turbid, abandoning potentially hazardous materials and seeking others to quarantine to keep the body healthy.
Damage or interruption to this system can result in a range of medical conditions. You may be familiar with lymphedema, a condition in which lymph pools in the limbs because it cannot circulate. Lymphoma is also related to the lymphatic system, as the name implies, and elephantiasis is also linked with disruption to the lymphatic system. You may also notice that your lymph nodes become swollen when you are sick, because your body is isolating the agent responsible to help you get better.