A galaxy is a group of stars that exists in the universe. Scientists think that there might be over 100 billion galaxies out there.
Galaxies are big and they have stars that spin around the center. We live in the Milky Way galaxy where there are 300 billion stars, which also contains our solar system.
There are four types of galaxies and they are grouped by shape. These types are spiral, barred spiral, elliptical, and irregular. Andromeda is our closest neighboring galaxy and is 2.6 million light years away from us. Galaxies are really big and interesting.
[Source: The Smithsonian]