On definition is that it is a style of music that arose in the early 1970's in the UK.
On the KVRaudio forum, the question of "Why the term Prog" came up. Here is one of my quotes that may shine light on the subject.
"I agree with you. It is a bit silly that the whole world has decided on
the word "prog" rock. Symphonic rock and Art rock are good terms, but I
guess the general public got confused.
So whether we like it or not, the term "prog" is here to stay because
people always have the need to label things, and I guess I can live
with that. The good thing is that when I say "Prog" at least people
know exactly the era and bands I am refering to."
