A galaxy is a huge collection of stars, gas, and dust that are held together by gravity. There are billions of galaxies in the universe, and each one is unique. Our own galaxy, the Milky Way, is shaped like a big, flat disk and has a bright center where many of the oldest and most massive stars live.
Galaxies can be found in all sorts of shapes and sizes. Some are small and faint, while others are massive and bright. Some are shaped like disks, like the Milky Way, while others are more irregular in shape.
Inside a galaxy, the stars are held together by the gravity of all the other stars. They orbit around the center of the galaxy, just like how the planets in our solar system orbit around the sun. The center of a galaxy is usually where you’ll find the most old, massive stars, as well as a supermassive black hole.