Antimatter is the opposite of normal matter. The sub-atomic particles of antimatter have properties opposite those of normal matter. The electrical charge of those particles is reversed. Antimatter was created along with matter after the Big Bang, but antimatter is rare in today's universe, and scientists aren't sure why. Antimatter particles are created in ultra high-speed collisions. In the first moments after the Big Bang, only energy existed. As the universe cooled and expanded, particles of both matter and antimatter were produced in equal amounts. Why matter came to dominate is a question that scientists have yet to discover. One theory suggests that more normal matter was created than antimatter in the beginning, so that even after mutual annihilation there was enough normal matter left to form stars, galaxies and us. In the case of antimatter, the electrical charge is reversed relative to matter. Anti-electrons (called positrons) behave like electrons but have a positive charge. Antiprotons, as the name implies, are protons with a negative charge.  When antimatter particles interact with matter particles, they annihilate each other and produce energy. This has led engineers to speculate that antimatter-powered spacecraft might be an efficient way to explore the universe. This propulsion could solve many of the problems we face today in our current space exploration. We could go on long distance trips without the worry for fuel. This solution is in the near distant future but it could help us a lot.