For every type of matter particle, there is a corresponding antimatter particle. Antiparticles look and behave just like their corresponding matter particles, except they have opposite charges.
Antimatter particles are created in ultra high-speed collisions. In the first moments after the Big Bang (learn more about it in my previous article Origin of our universe), only energy existed. As the universe cooled and expanded, particles of both matter and antimatter were produced in equal amounts. And the biggest question for which we have no answer yet is, why there is more matter than antimatter in the universe??
For instance, a proton is electrically positive whereas an antiproton is electrically negative and gravity affects matter and antimatter the same way, because gravity is not a charged property and a matter particle has the same mass as its antiparticle
In 1928, British physicist Paul Dirac came up with an equation that combined quantum theory and special relativity ( learn more about it here Special relativity), just a simple one x2=4, this equation can have two possible solutions (x=-2 or x=2), one for an electron with negative energy, and one for an electron with positive energy.
HOW CAN WE USE ANITIMATTER?
The most interesting and even frustrating fact about antimatter is, when matter and antimatter come into contact, they disappear producing energy (annihilate is the technical term for it). This led scientists to think of antimatter-powered spacecraft for more efficient space exploration. Of course that costs billions of dollars though..
Now, the frustrating part is, it is damn tough to contain antimatter because all our equipment is made of matter and as we try to put them in any of those containers, they disappear leaving back some energy. But scientist have managed to contain some antimatter for about 15 minutes, sufficient for scientific study.
So, do you have any clue about having more matter than antimatter?
Wanna know what dark matter is? visit Dark matter.