Blood plasma that escapes from the blood vessels is absorbed into the surrounding tissue. This tissue fluid collects in tubes throughout the body and is known as lymph. From the lymph tubes, it returns to the blood after passing through a lymph node. If you've ever broken a blister, you've seen lymph. It's a colorless, slightly sticky liquid.
Lymph is an important part of the circulatory system. It aids the body's absorption of nutrients and helps to remove waste from the tissue. The lymph collects the body's waste and then deposits it in a lymph node as it passes through. Lymph nodes are clumps of tissue that collect the waste deposits. Your tonsils and adenoids are two examples of lymph nodes.
The lymph nodes also assist the spleen and the bones in producing new white blood cells.