Antimatter
Antimatter is matter composed of the antiparticles of the corresponding particles in ordinary matter. Some properties of an antiparticle are the same as those of the ordinary particle, but other properties (including the electrical charge) are exactly opposite. If a particle and its antiparticle meet, they will destroy or annihilate each other converting the entire mass into energy (E). According to the German physicist Albert Einstein (1879 - 1955), the following relation holds:E = m × c2
Here, m is the mass and c is the speed of light.