Extracellular fluid (ECF) is the fluid found outside of cells in the body. It plays a crucial role in transporting nutrients, waste products, and signaling molecules between cells and their environment. ECF includes various components, such as interstitial fluid, which surrounds cells, and plasma, the liquid part of blood. The balance of extracellular fluid is essential for maintaining proper cell function and overall health. It helps regulate blood pressure, electrolyte levels, and temperature. Any disruption in the composition or volume of ECF can lead to health issues, highlighting its importance in physiological processes.