Intracellular fluid is the fluid that exists within the cells of multi-celled organisms. The intracellular fluid is therefore stored within the intracellular compartments of the body. Intracellular fluid is often referred to as cytosol when discussing cellular functions. The cytosol and the organelles and molecules contained within are referred to collectively as the cytoplasm. The opposite of the intracellular fluid is the extracellular fluid, which exists on the outside of the cells in the extracellular compartment of the body