Lymph is a clear, colorless fluid that circulates throughout the lymphatic system, which is a part of the body's immune system. It is composed of water, proteins, and white blood cells, particularly lymphocytes, which help fight infections. Lymph collects waste products, bacteria, and excess fluid from tissues, transporting them to the bloodstream. The lymphatic system includes lymph nodes, which filter lymph and trap harmful substances. As lymph moves through the system, it passes through these nodes, where immune responses can be activated. This process is essential for maintaining fluid balance and supporting the body's defense against diseases.