We live in an isolated collection of 100 billion stars called a galaxy . There are probably 100 billion such galaxies scattered throughout the universe. Most of these stars lie in a highly flattened disk which is about 30,000 parsecs across but only a few hundred parsecs thick. Some stars lie in a tenuous spherical halo which surrounds the disk.
Gravity holds the galaxy together.
The stars in the disk travel in approximately circular orbits about the center of the galaxy. At this velocity the Sun completes a trip around the center of the galaxy in about 200 million years. The oldest stars reside in the galactic halo. The Sun is only 4.6 billion years old.