Dark matter from what I understand acts as an anti-gravitional force, causing matter to push apart rather than accumulate as in the case of gravity, which would explain why it doesn’t accumulate and form dark matter galaxies and so forth.
Scientists theorized it as an explanation for why the universe appears to be ramping up its expansion instead of collapsing back in on itself.
Ehh.. scratch that. That was dark energy, not dark matter. I keep getting the two mixed up.