What is/was "Anti Matter"?

Anti-matter is the same size and mass of regular matter, but has an opposite charge.

So for example, the anti-particle of an electron is a positron. Its exactly the same size, mass as an electron, but has a positive charge.

When mater and anti-matter meet, the completely annihilate each other, turning into pure 100% energy

In particle physics, antimatter is the extension of the concept of the antiparticle to matter, where antimatter is composed of antiparticles in the same way that normal matter is composed of particles. For example, a positron (the antiparticle of the electron or e+

) and an antiproton (p) can form an antihydrogen atom in the same way that an electron and a proton form a normal matter hydrogen atom. Furthermore, mixing matter and antimatter can lead to the annihilation of both in the same way that mixing antiparticles and particles does, thus giving rise to high-energy photons (gamma rays) or other particle–antiparticle pairs.

There is considerable speculation as to why the observable universe is apparently almost entirely matter, whether there exist other places that are almost entirely antimatter instead, and what might be possible if antimatter could be harnessed. At this time, the apparent asymmetry of matter and antimatter in the visible universe is one of the greatest unsolved problems in physics. The process by which this asymmetry between particles and antiparticles developed is called baryogenesis.

anti matter is the opposite of normal matter. It would have opposite charge and spin.

For example, and electron has an anti particle known as a positron. Same mass, but it has a positive charge and opposite spin.

Matter that is made from the "symmetric" particles.

For example, the "normal" carrier of the negative electrical charge is the electron. There exists a particle that is exactly like the electron, but it carries a positive charge. This particle is an "anti-electron" (used to be called a "positron").

The normal hadron with the positive charge, forming the charged portion of the atomic nucleus, is the proton. There exists a particle that is exactly like a proton, except that it carries a negative charge. This is an anti-proton.

If you can get an anti-electron to orbit around an anti-proton, you would have an atom of "anti-hydrogen".

For some reason, our universe is mostly made of "normal" matter. However anti-matter is not impossible (and we can make anti-matter, in very small quantities, in labs).

The problem is that if matter and the corresponding anti-matter come in contact, then they "cancel" each other out and all their mass is transformed into energy (E = m c^2). Therefore, it is very difficult to keep large amounts of anti-matter (what do you keep it in?).

protons are made of quarks. anti-protons are made of anti-quarks.

there are also anti-neutrons (made of anti-quarks)

All particles have a corresponding anti-particle, except that some particles seem to be their own anti-particle (for example, the photon - since it is already pure energy, then it does not matter if it meets "itself", it is already in the form of energy).

In 1928,Paul Dirac,came up with a theory that showed that FOR EVERY CHARGED PARTICLE,THERE SHOULD BE A PARTICLE WITH AN OPPOSITE CHARGE BUT THE SAME WEIGHT.Thus,he predicted that there should be an anti-electron,a particle with a same mass as that of the electron but with a positive charge.In 1932,Carl Anderson discovered positron which is a anti-electron.

Anti matter is the matter consisting of elementary particles that are the antiparticles of those making up normal substances