Antimatter refers to a type of matter composed of particles that have opposite charges to those of normal matter. Each fundamental particle that makes up normal matter (such as electrons and protons) has a corresponding antiparticle, which constitutes antimatter.
For example, the antiparticle of an electron is called a “positron,” which has the same mass as an electron but carries a positive charge. When antimatter comes into contact with regular matter, the two annihilate each other, releasing a large amount of energy in the process. This phenomenon is known as “annihilation.”
Theoretically, antimatter should have existed in equal amounts with regular matter in the early universe. However, for reasons not yet fully understood, the universe today is dominated by regular matter, with very little antimatter present. This discrepancy is one of the major unsolved mysteries in physics.