Osmosis: The movement of water molecules from an area of high concentration to an area of low concentration.
All cells are permiable thus allowing the movement of water from the outside of the cell to the inside.
Hypotonic Solution: the cell has a higher concentration in it than in the area surrounding it. Water moves into the cell to equal out concentration.
Isotonic Solution: The cell has a equal proportion of concentration with the area surrounding. Water continually flows in and out to keep concentration even.
Hypertonic Solution: Concentration of the cell is less than outside of the cell. Water moves out of the cell to try to even out the concentration.