M20 is a red emission nebula with a young star cluster located at its center. The astronomer John Herschel was the first to use the term, "Trifid" to describe this nebula's appearance. Charles Messier referred to M20 only as a "cluster of stars".

The nebula is located close to M8, the Lagoon Nebula, in the night sky. Both objects are easy to locate, making them popular targets for astrophotographers.