What are the conditions required for endosmosis and exosmosis?

Endosmosis refers to the inward movement of water from the surrounding environment into the cell through the cell membrane. It can only take place if the cell is placed in a hypotonic solution wherein the solute concentration of the cytoplasm inside the cell is higher than the solute concentration of the surrounding solution. The difference in concentration causes water to flow into the cell to achieve equilibrium on both sides of the cell membrane.  

Exosmosis refers to the outward movement of water from the cell to the surrounding environment through the cell membrane. It can only take place if the cell is placed in a hypertonic solution wherein the solute concentration of the cytoplasm inside the cell is lower than the solute concentration of the surrounding solution. The concentration gradient causes water to flow out of the cell to achieve equilibrium on either side of the cell membrane.