Colligative properties are physical properties of solutions that depend on the number of solute particles present, rather than their identity. These properties include boiling point elevation, freezing point depression, vapor pressure lowering, and osmotic pressure. They are important in various scientific and industrial applications, such as in determining the concentration of solutions. The effects of colligative properties arise when a solute is added to a solvent, altering the solvent's behavior. For example, adding salt to water increases its boiling point and decreases its freezing point. Understanding these properties helps in fields like chemistry, biology, and engineering.