Question

What stops the stars that make the galaxy from just straying off on their own? How does eveyrthing stay together?

Answer 1

One word: Gravity.

Explanation:

Generally, the galaxies center will keep it together. What is this center? Generally, a black hole, aka Quasar, aka Blazar, aka singularlity. This object has so much gravity, everything in the galaxy stays attracted to it. That's why it's the center. Stars will stray from it sometime though (but not from the galaxy). The entire galaxy rotates around the center. The Black Hole at the center keeps everything together. (That's a rhyme for remembering).