Expansion of the universe

Expansion of the universe means that all of the galaxies, stars and other things that are in space are getting farther away from each other. This happens because space itself is growing or expanding. Think of it like a balloon that you blow up with air. As the balloon gets bigger, all of the things on the balloon (like stars and galaxies) are getting farther apart from each other, even though nothing is actually moving. So all of the galaxies, stars and other things in space are getting farther away from each other because space itself is expanding.