In the most widely accepted explanation called the Standard Model, all the matters in the universe are made up of 12 elementary particles. Six of these are called quarks and the other six, leptons. Protons and neutrons are made by combining 3 quarks, while an electron is a kind of lepton. All of the particles have their antiparticles.
Antiparticles have an electric charge opposite from their corresponding particles. However, all of the other properties, such as mass, are the same. To name an antiparticle, you can generally put "anti" in front of the particle name. An example of this is antiproton. There is one exception, however, and that is positron, the antiparticle of electron. Electrically neutral particles are their own antiparticles.
The existence of antiparticles was first theorized by Paul Dirac. His calculations to incorporate Einstein's theory of relativity to quantum theory yielded the existence of positron. A positron has the same mass as electron but is positively charged. The evidence for the existence of antiparticles was first seen in cloud-chamber experiments.