The Green Room

For me, the green room was a place where you could bump into other performers, have casual conversations and make arrangements for future collaborations. Let's use this area of the forum to do that.

"Green refers to the light above the entrance to the room. The light could alternatively be red. If the light is red you are being told not to enter the room. If the light is green you can enter the room. Typically a green room is where guests wait and are entertained before entering a television studio. You could think of a green room as a welcoming area from which people enter an exclusive area. A green room need therefore be neither green nor a room."

https://www.theguardian.com/notesandqueries/query/0,5753,-5622,00.html