CPT symmetry is a fundamental principle in physics that states the laws of physics should remain unchanged when three transformations are applied: C for charge conjugation, which swaps particles with their antiparticles; P for parity transformation, which flips spatial coordinates; and T for time reversal, which reverses the direction of time. This symmetry suggests that the behavior of particles and their interactions should be the same when these transformations are applied. In particle physics, CPT symmetry is crucial for understanding the behavior of subatomic particles. It implies that if we could observe a universe where all particles are replaced by their antiparticles, spatial coordinates are inverted, and time runs backward, the physical laws would still hold true. This principle helps physicists ensure that their theories are consistent and can predict the outcomes of experiments accurately.