Cytosol

Cytosol is the fluid found inside cells. It is separated within a cell by membranes and contained within a cell wall. The majority of the fluid is water, but it contains a complicated mix of substances. Despite being studied for centuries, the function of cytosol is still poorly understood, largely because many of its functions are carried out at the microscopic level and can only be observed within an intact functioning cell. However, it is known it plays an important role in the regulation of the flow of ions into and out of the cell and is capable of concentrating or diluting the concentration of ions such as sodium and potassium in different parts of the cell to regulate osmosis. About 20-30% of cytosol is various proteins. It is also known that cytosol does not serve a single function in the cell and instead is responsible for multiple function.
Cytosol at Wikipedia