"I know I'm not a man...and I've come to the conclusion that I'm probably not a woman either. The trouble is, we're living in a world that insists we be one or the other."
First of all LGBT stands for Lesbian, Gay, Bisexual, and Transgender. Lesbian is typically defined as a woman attracted to another woman. Gay is men who are attracted to other men, but can also be used as an umbrella term for the entire LGBT community. Bisexual is a label used for a person who is attracted to two sexes or genders but not necessarily equally or simultaneously. This term is limiting as it states that there are two sexes, male and female, which excludes those who are intersex or transsexual. Bisexual also assumes that there are two genders excluding transgender as well. Some might feel that gender and sexuality are set in stone, but I feel that there is a lot of fluidity in sexuality and gender. Transgender refers to someone whose gender identity differs from the social expectations of the physical sex they were born with, like a masculine woman or feminine male or some variation. Transsexual is a term used to define a person who identifies as the opposite of the sex they were born with and may undergo medical treatment like hormone therapy, top, or bottom surgery.
Queer is a term used both as a political statement and a sexual orientation. This term advocates breaking binary thinking and seeing both sexual orientation and gender identity as fluid. Some members of the LGBT community view this term negatively as it was used by straight people in the past as an insult. Pansexual is a term used to describe those who are fluid in sexual orientation and/or gender identity. Genderqueer is a term used to describe a person who plays with gender or refuses gender altogether. Gender is defined as a social construct that qualifies certain things as masculine or feminine. Sex refers to sex organs. An ally is someone who advocates for and supports members of a community other than their own.
Knowing what these terms mean can help someone better understand how to be an ally for the LGBT community. It's helpful for people who may have a friend, family member, or co-worker who is in the LGBT community. It is also helpful for people within the LGBT community to know what these different terms mean because for example, a gay male may not understand the difference between transgender and transsexual. Ultimately with any label or term it is best to just ask the individual what the term means to them as everyone has a different interpretation on their own representation.