Okay kiddo, have you ever looked up at the night sky and noticed those pretty twinkling lights? Those are stars! And you've probably seen pictures of colorful clouds of gas and dust in space, right? Those are called nebulae.
Now, sometimes those nebulae can be really, really dark - almost like someone took a giant ink blot and covered up the stars behind them. Those are called dark nebulae.
It's like when you hold your hand up to the sun and it casts a shadow on the ground. The dark nebula is like a cloud of dust and gas that's so thick that it blocks out the light from the stars behind it, casting a shadow in space.
Scientists think that these dark nebulae are where new stars are born! The gas and dust in the nebula can eventually collapse in on itself because of gravity, until it becomes so dense that it ignites and becomes a star.
So even though dark nebulae might look like giant black clouds in space, they're actually really important because they're where new stars are born. Cool, huh?