Every particle in the universe has an anti-particle. If the particle and its anti-particle come into contact, they will annihilate each other in a great flash of light at an intensity of one photon. There is a very interesting question though. Why are there more particles than anti-particles in the universe? Some physicists have been able to answer this question through a series of experiments.
According to the Grand Unified Theory; or a theory that unifies electromagnetic, strong, and weak forces; at high energy, quarks are able to change into anti-electrons. This process is also possible in reverse fashion. So, during the early stages of the universe, when vast amounts of heat and energy were present, these transformations could have occurred. The reason why anti-particles turned into quarks was because the laws of physics for particles are not the same for anti-particles.