Stellar pulsation refers to the rhythmic expansion and contraction of a star's outer layers. This process occurs due to changes in temperature and pressure within the star, causing it to brighten and dim over time. Different types of stars exhibit varying pulsation patterns, with some pulsating regularly while others do so irregularly. One well-known example of a pulsating star is the Cepheid variable, which has a predictable cycle of brightness changes. These stars are crucial for astronomers, as their pulsation periods can be used to determine distances in the universe, helping to map the cosmos more accurately.