What is a flattened combination of matter containing stars gas and dust in a spiral galaxy can be identified as what?

A flattened combination of matter containing stars, gas, and dust in a spiral galaxy can be identified as the galaxy's disk. This structure typically features spiral arms that extend outward from the center, where the galaxy's bulge and often a supermassive black hole are located. The disk is where most of the galaxy's star formation occurs, making it rich in both young and old stars, as well as interstellar material.