funny how people call it the "gay rainbow". there's nothing inherently gay about it. it's a rainbow in one of its most simplest permutations.
however, if used as a banner or a flag, it's a pride flag, symbolic of gay pride, lesbian pride, GLBT pride, queer pride, whatever.. that's what i always learned it as. what the rainbow comes to stand for, however, is a bit tricky. most people say it represents diversity ..in orientation or sexual practices. i think that's true but i believe it more to be representative of the continuum of sexuality. that sexuality isn't so black and white as people are wont to think.
its usage is another thing. folks say that they find it annoying that someone were to announce their sexual orientation like that. this brings in the whole pride thing and solidarity thing that someone else brought up. much like a flag of some nation out for the world to see in the form of a bumper sticker or whatnot, it shows an individual pride in what and who the person is. be it italian or irish or gay. and despite what people may think, gay is also a culture and not just a sexual preference.
now, what's so wrong with being proud of who or what you are?
now, as for me, i find this topic interesting. i mean, as an oppressed people, signs are developed so that one could spot one of their own. ..a hidden language of signals and whatnot. spotting a pride flag and recognizing it for what it is ensures a kind of safety and familiarity. usually the ones who can recognize it are those who are knowledgeable of such things and not the bashers and violent types that are unwelcomed by these peoples.