Particle decay is a fundamental process in particle physics where a particle transforms into one or more other particles. This process occurs when a particle is unstable and undergoes a change in its internal structure, resulting in the emission of new particles. Particle decay plays a crucial role in understanding the properties and behavior of subatomic particles, as well as in determining their fundamental interactions and forces. By studying particle decay, scientists can gain insights into the underlying physics principles and the fundamental building blocks of matter.