The full term is LGBTQIA. Here's a nice explanation for it:
http://tahoesafealliance.org/for-lgb...-lgbtqia-mean/
PSN: LydonMcG
It can get complex. It's sort of an umbrella term for any minority non-binary sexual orientation. People who feel they aren't represented by the "broader" identities (Gay, Lesbian, Transgender, Intersex) sometimes choose to just identify as "Queer".
As an example, if you're a transgender man, who still likes men - are you gay? Are you a straight transgender? Where do you fit into the "broader" scheme of things? Some people even consider asexuals as falling into the "Queer" category.
For a lot of people there simply is no 'category' you fall into, so identifying as "Queer" solves that, because it's basically a catch-all. Gay people can identify as Queer as well, even if they match the broader category.
There's a lot of debate about it, but what I think it boils down to is that it's not for anyone else to categorise who you are.
That is, If you don't get why Queer as a "label" is needed, or see the difference, it's almost irrelevant, because that means it's obviously not meant for you
The idea is to be as inclusive as possible.