In biology, a hypotonic solution is a solution that has a lower concentration of solutes compared to another solution to which it is compared. When a cell is placed in a hypotonic solution, there will be a net flow of water into the cell, and the cell will gain volume. The majority of times, the solution of comparison is the cytosolic fluid or the fluid present inside a cell. Hypotonicity is a relative term wherein the property of the solution is defined relative to the other solution. The cell membrane is the semipermeable membrane, and a hypotonic solution is a solution that has lower osmotic pressure than another solution to which it is compared. A hypotonic solution is used in laboratory techniques, such as cell culture, to promote cell swelling and lysis. In contrast, hypertonic solutions are used to dehydrate cells and tissues.