Particle-antiparticle interactions occur when a particle, such as an electron, meets its corresponding antiparticle, like a positron. These interactions can lead to annihilation, where both particles are converted into energy, typically in the form of gamma-ray photons. This process illustrates the principle of mass-energy equivalence, as described by Albert Einstein's famous equation, E=mc². In addition to annihilation, particle-antiparticle pairs can also form through high-energy collisions, creating a temporary state known as a virtual particle. These interactions are fundamental in quantum field theory and play a crucial role in understanding the behavior of matter and antimatter in the universe.