Colligative properties are properties of solutions that depend solely on the number of solute particles dissolved in the solvent, regardless of their chemical identity. Here are four important colligative properties of solutions:

1. Boiling Point Elevation: Boiling point elevation refers to the increase in the boiling point of a solvent when a non-volatile solute is dissolved in it. The presence of solute particles disrupts the vapor pressure of the solvent, requiring a higher temperature to reach the vapor pressure equal to the atmospheric pressure. The magnitude of boiling point elevation depends on the concentration of the solute particles. This property is utilized in various applications such as antifreeze solutions in vehicles and in cooking processes like brining.
2. Freezing Point Depression: Freezing point depression is the lowering of the freezing point of a solvent when a solute is dissolved in it. The solute particles interfere with the formation of the regular crystal lattice of the solvent, making it more difficult for the solvent to solidify. Consequently, the freezing point decreases. Freezing point depression is commonly observed in saltwater solutions used for de-icing roads and in antifreeze solutions to prevent engine coolant from freezing.
3. Osmotic Pressure: Osmotic pressure is the pressure applied to prevent the flow of solvent molecules into a solution through a semi-permeable membrane. It is a colligative property dependent on the concentration of solute particles. When a solution with a higher solute concentration is separated from a solution with a lower solute concentration by a semi-permeable membrane, the solvent molecules tend to move from the region of lower solute concentration to the region of higher solute concentration, resulting in osmosis. Osmotic pressure has important biological implications, such as in cellular processes and osmoregulation.
4. Vapor Pressure Lowering: Vapor pressure lowering refers to the reduction in the vapor pressure of a solvent when a non-volatile solute is added. The presence of solute particles on the liquid surface interferes with the escape of solvent molecules into the vapor phase, thus decreasing the vapor pressure. The extent of vapor pressure lowering is directly proportional to the concentration of solute particles in the solution. Vapor pressure lowering is used in applications such as in the preservation of food by canning.

These colligative properties provide valuable insights into the behavior of solutions and find applications in various fields such as chemistry, biology, medicine, and industry.