Why is the band Phish so popular?
Phish have taken influences from many genres of music including rock, metal, blues, jazz, country, latin, barbershop quartet, and americana and blended it into their own take on improvisational jam band rock.  Their music often contains sections that are composed interspersed with long improvisational passages.  Each time you hear one of their songs, in part, it has never been heard before.  The setlists of their live shows are never been repeated, each one is different.  Each of the musicians is virtuosic in their instrument - Trey Anastasio on guitar, Page McConnell on Keyboard, Mike Gordon on bass, and Jon Fishman on drums.  Their live shows are high energy and the music takes fans on a journey.  Their lighting director, Chris Kuroda, is known as the fifth member of the band as the lighting meshes seamlessly with the music.  Phish has been together since 1983 and over the course of the past 40 years they have hundreds of original songs as well as incorporating their own take on many cover songs.  The lyrics range from whimsical to melancholic but are more often geared towards the whimsical side.  Phish is regarded as being one of the most influential bands, along with the Grateful Dead, in the jam band music scene.  Like the Grateful Dead, their fans tend to be incredibly devoted, often traveling to see many shows in a single tour.