A galaxy is a massive, gravitationally bound system that consists of stars, stellar remnants, an interstellar medium of gas and dust, and dark matter. Galaxies are the building blocks of the universe, and they come in various shapes and sizes.
There are three main types of galaxies:
Galaxies are thought to have formed from the gravitational collapse of clouds of gas, and they continue to evolve through interactions with other galaxies. The study of galaxies and their formation is an important area of research in astronomy.