Periodic comets are celestial objects that orbit the Sun in predictable paths, returning to the inner solar system at regular intervals. Unlike irregular comets, which can have highly eccentric orbits, periodic comets have more stable trajectories, allowing astronomers to anticipate their appearances. Famous examples include Halley's Comet, which returns approximately every 76 years. These comets are often categorized based on their orbital periods, with short-period comets taking less than 200 years to complete an orbit. The study of periodic comets helps scientists understand the composition of the early solar system and the dynamics of celestial mechanics.