Pulsating stars are a type of variable star that change in brightness over time due to periodic expansions and contractions of their outer layers. This behavior is often caused by internal processes, such as changes in temperature and pressure, which lead to oscillations. Common examples of pulsating stars include Cepheid variables and RR Lyrae stars. These stars can be important for astronomers because their pulsation periods are related to their intrinsic brightness. By measuring the pulsation period, scientists can determine the distance to these stars and, consequently, to the galaxies they reside in, aiding in the understanding of the universe's structure.