It's basically like initials. Lesbians,gay,bisexual,and transgender. It describes someone's interest and what they feel they are. How a person feels about someone or them selves.
How do they know there in the LGBT?
Well, if your in any if this categories then your in it. It's okay.
Is it wrong?
To be honest I think it's alright. It's not wrong. Who cares if they like people from the same sex and want to be together or they want to switch genders. It's alright. Love is love. And there's really nothing else to say about it. So no it's not wrong. It's right.
What if I'm straight and they like me?
Well, just tell them I'm sorry but I'm not in any category in the LGBT. You don't have to be a jerk about it or change your friend ship. Just tell them I'm straight I'm sorry. That's it. And go on to being back the way it was.
What am I?
Well that depends on you. I'm personally gay. I like guys instead of girls. What ever you feel you like.