What even is Bluegrass?

Bluegrass us a genre of music that was started by Bill Monroe in the 1940s. It got its name from the band Bill Monroe and the Blue Grass Boys.

It's sometimes hard to describe Bluegrass, but we always say you know it when you see it. If you want to be a purist, you can say Bluegrass music is based on the same instrumentation Bill Monroe had in his original band: Guitar, Mandolin, Fiddle, Banjo, and Upright Bass. No drums. We're gonna say that again, no drums. 

Do you want more? Click this wikipedia link and it will give you the full rundown.