What is Cold dark matter (CDM)?

Cold dark matter is like invisible jellybeans hiding inside our universe’s candy jar.

Imagine you're playing hide-and-seek in a big room full of furniture. You can’t see the people who are hiding, but you know they’re there because when you count, some people are missing, and then suddenly they pop out from behind the couch! Dark matter is like those hidden players: we can't see it, but we know it's there because it affects how things move.

Now imagine those jellybeans aren’t just hiding, they’re slow-moving. They don’t zoom around like hot lava or bounce like a ball. That’s what makes it cold dark matter: it moves slowly, like sleepy jellybeans in a jar.

Scientists think these slow-moving invisible jellybeans help hold galaxies together, kind of like how glue holds pieces of paper together, you can't see the glue, but it's there, doing its job quietly and steadily.