All material that we see, taste and touch is made of tiny particles called atoms. The atom is the smallest portion of an element, like lead or oxygen or carbon, that is still considered to be that element.
Protons have a positive electrical charge and electrons a negative charge.
The answer is anti-matter. Material, like we see all around us, but with a reversed charge. The problem is that it isn't all around us. In fact, it doesn't seem to exist in large quantities anywhere in the Universe. Because of this it is easy for scientists to tell that no significant mass of anti-matter exists in our solar system.