Everything around us is made of matter created from Big Bang. Particle accelerator revealed that 2 types of particles are produced in equal parts during Big Bang. One is the type of matter we see around us. Other is the opposite called anti-matter.
Anti-matter is similar to matter except some basic properties.
Matter and anti matter cannot co exists. Matter and anti matter destroy each other when they come in contact with each other. One orange size matter and anti matter will release energy equivalent of 10 megaton nuclear bomb. Since matter and anti matter are created in equal numbers, all matters should be destroyed when this battle was over. So there will be no matter to create our universe. But universe exists and so does we. Then how did matter defeat anti matter. It is one of the great mysteries of our universe.
One theory says anti-matter is less stable and decays more quickly. This gives matter slight advantage in the fight between matter and anti-matter. That eventually led matter victorious over anti-matter. But scientists are not sure about it. But it is certain that something happen that allows matter to win against anti matter so we can live in our current universe.
There is a possibility of parallel universe like us composed of antimatter. It is still a mystery of our universe yet to be solved.