Interstitial fluid is a clear, colorless fluid that fills the spaces between cells in tissues. It serves as a medium for the exchange of nutrients, waste products, and gases between blood and cells. This fluid is essential for maintaining a stable environment for cells, allowing them to function properly. The composition of interstitial fluid is similar to that of blood plasma but contains fewer proteins. It plays a crucial role in the lymphatic system, which helps drain excess fluid and return it to the bloodstream. Proper balance of interstitial fluid is vital for overall homeostasis in the body.