What Is Dark Matter — And Why Does It Matter?

Dark matter is like an invisible friend that helps hold the universe together. Imagine you're playing with building blocks, and even though you can see the blocks, there's something else holding them all in place, something you can’t see. That’s dark matter. It doesn’t shine or glow, but it has mass, which means it pulls on things like stars and galaxies. Scientists think dark matter is everywhere, it helps keep galaxies from flying apart, just like glue holds your blocks together.