I'm guessing you've never been?
That's ok best just stay away you would hate it.
Seriously it is "Glasto code" for there are over 100 stages at Glastonbury, there is a Circus tent, a comedy tent, cinema, bars, wonderful food of just about every sort you could imagine, entertainers strolling around the site, etc. etc., you could easily have the time of your life and never go near one of the stages listed on the poster.
I've been there in the mud, the pouring rain and in the sun and still would love to be going this summer even though the headliners are a bit "meh".