Cepheid Variables are a type of star that pulsates in a regular cycle, changing their brightness over time. These stars expand and contract, which causes them to brighten and dim in a predictable pattern. The period of their pulsation is directly related to their intrinsic brightness, making them important tools for measuring distances in the universe. Astronomers use Cepheid Variables to determine how far away galaxies are from Earth. By observing the pulsation period and calculating the star's true brightness, they can compare it to how bright it appears from our perspective. This method has helped refine our understanding of the size and scale of the universe.