Dark matter is a hypothetical type of substance that has mass and takes up space.
=== Based on elementary fermions (mass, volume, and space) ===A common or traditional definition of matter is "anything that has mass and volume (occupies space)"
 Baryons and leptons can be created, but their creation is accompanied by antibaryons or antileptons; and they can be destroyed, by annihilating them with antibaryons or antileptons

