Technically, they didn’t! The universe is constantly expanding, and the stars and galaxies are constantly moving. But galaxies have a black hole in the center which keeps the entire galaxy together by its enormous gravitational pull. That’s how solar systems like our own can exist within specific galaxies rather than just float through space alone.

Stars definitely have a gravitational pull! In fact, it is the gravitational pull of the sun which keeps Earth in orbit in our solar system. Actually, anything with mass has a gravitational pull. The Earth has a gravitational pull which keeps the moon in orbit. The moon has a gravitational pull which creates tides. Even you and I have a gravitational pull! The strength of an object’s gravitational force depends on its mass, so something that is very big and has a lot of mass like the sun has a large enough gravitational force to keep planets in orbit whereas you or I have such a weak gravitational pull that it has virtually no effect on our surroundings.

The gas which formed stars was brought together and held together by gravity. Gravity is also what compresses that gas to start the fusion reactions that turn them from collections of gas into stars, as well as keeping them together against the outward push from those fusion reactions. These stars also have a gravitational pull.

If stars did not exert a gravitational pull on other objects, then Earth would not orbit around the sun.

Gravity is the term used to describe the phenomenon that everything with mass pulls on everything else with mass.

Stars, like everything else, have mass, and, like everything with mass, they exert gravity. This is absolutely necessary to keep stars from blowing themselves apart, since the nuclear reactions that power them are the same as those taking place inside of a hydrogen bomb. Stars are, for all intents and purposes, atomic fireballs of thermonuclear explosions that are held together by their own gravity.