A galaxy is a system which contains a collection of stars, stellar remnants, interstellar gas, dust, dark matter, and their solar system, which is all held together by gravity. 

The word gravity was taken from the greek word ‘galaxias (γαλαξίας)’ meaning ‘Milky’ which is a reference to our galaxy ‘The Milky Way’.

There are more than 200 billion galaxies in the universe, each presenting beautiful structures that can be seen in telescope images taken of the distant universe. 

Galaxy’s range in size, from dwarf sized galaxies containing millions of stars to supergiant’s containing trillions of stars, where each galaxy’s stars are orbiting their galaxies’ centre of mass.

Almost every known galaxy has a supermassive black hole in its centre, which also plays a part in determining the galaxy’s characteristics.