The Lymphatic System is one of the two systems of circulation of fluid around the body (the other being blood circulation).
The lymphatic system consists of lymphatic fluid (called "lymph") flowing through a system of lymphatic vessels, including lymphatic capillaries, other lymphatic vessels of various sizes (which can be compared with blood vessels), and lymph nodes(which are encapsulated masses of B Cells and T Cells).
The Blood System and the Lymphatic System are interconnected. The clear fluid that is known as "lymph" when flowing through the lympatic vessels, initially passes into those vessels as "interstitial fluid" contained in spaces between tissue cells - spaces into which it had been filtered from blood.