Here's the breakdown:

* Meteoroid: A small rocky or metallic body in space.

* Meteor: The bright streak of light we see when a meteoroid burns up in the Earth's atmosphere. This is often called a "shooting star."

* Meteorite: A meteoroid that survives its passage through the atmosphere and lands on Earth.

So, when a meteoroid enters the atmosphere, it becomes a meteor. If it survives and hits the ground, it becomes a meteorite.