Antimatter

Antimatter is a term in particle physics. Antimatter is a material composed of antiparticles. These have the same mass as particles of ordinary matter but have opposite charge and properties, such as lepton and baryon number.

Encounters between a particle and an antiparticle led to both of them being destroyed. This gives rise to high-energy photons (gamma rays), neutrinos, and lower-mass particle–antiparticle pairs.