A huge group of stars, gas and dust in space is called a galaxy.
Galaxies are enormous systems held together by gravity. They can contain millions, billions or even trillions of stars, along with planets, nebulae, interstellar gas, cosmic dust and dark matter. Our Solar System belongs to the Milky Way Galaxy, a barred spiral galaxy.
Galaxies come in several broad shapes, including spiral, elliptical and irregular forms. The Milky Way and Andromeda are spiral galaxies, while elliptical galaxies are generally smoother and contain older stars. Many galaxies also have a supermassive black hole at their centre.
A common mix-up is confusing a galaxy with a solar system. A solar system is one star and the objects orbiting it; a galaxy contains vast numbers of stars and their planetary systems. Galaxies themselves can belong to groups and clusters, which are collections of many galaxies.