Explaining antimatter is complicated, but it's best to think of it as the mirror image of matter.
When matter and antimatter touch, they destroy each other in an huge burst of energy.
It is the only sort of energy imaginable that could power a star ship, although that is still a long way off.
Antimatter is very hard to make.
But scientists at Cern, Europe's enormous particle accelerator, have produced over 50,000 atoms of anti-hydrogen.
It's a tiny amount, so we're not in any danger of blowing up the planet, though it's still a huge step forward.