Dalton's Law is fundamental in understanding how gases behave in mixtures. It asserts that each gas in a mixture contributes to the total pressure in proportion to its amount (or partial pressure). This means that if you have a container with multiple gases, you can calculate the total pressure by simply adding up the pressures that each gas would exert if it occupied the entire volume alone. This law assumes ideal gas behavior, which means that the gases do not interact with each other and occupy the entire volume available to them without any intermolecular forces affecting their behavior. This principle is widely used in various scientific and engineering applications, including calculations in chemistry, physics, and engineering.