Transgender is a term used to describe people whose gender identity differs from the sex the doctor marked on their birth certificate. Gender identity is a person's internal, personal sense of being a man or a woman (or someone outside of that gender binary). For transgender people, the sex they were assigned at birth and their own internal gender identity do not match.
People in the transgender community may describe themselves using one (or more) of a wide variety of terms, including (but not limited to) transgender, transsexual and genderqueer. Always use the term preferred by the individual. Trying to change a person's gender identity is no more successful than trying to change a person's sexual orientation-it doesn't work. So most transgender people seek to bring their bodies more into alignment with their gender identity. Many transgender people are prescribed hormones by their doctors to change their bodies. Some undergo surgeries as well. But not all transgender people can or will take those steps, and it's important to know that being transgender is not dependent upon medical procedures.
Transgender is an adjective and should never be used as a noun. For example, rather than saying "Max is a transgender," say "Max is a transgender person." And transgender never needs an "-ed" at the end.
We use the acronym LGBTQ to describe the lesbian, gay, bisexual and transgender community. The first three letters (LGB) refer to sexual orientation. The "T" refers to gender identity. Sexual orientation describes a person's enduring physical, romantic and/or emotional attraction to another person (for example: straight, gay, lesbian, bisexual), while gender identity describes a person's internal, personal sense of being a man or a woman (or someone outside of that gender binary). Simply put: sexual orientation is about who you are attracted to and fall in love with; gender identity is about your own sense of yourself.
Transgender people have a sexual orientation, just like everyone else. Transgender people may be straight, lesbian, gay or bisexual. For example, a person who transitions from male to female and is attracted solely to men would typically identify as a straight woman. A person who transitions from female to male and is attracted solely to men would typically identify as a gay man.
You can't tell if someone is transgender just by looking.
Transgender people don't all look a certain way or come from the same background, and many may not appear "visibly trans." It's not possible to look around a room and "see" if there are any transgender people. (It would be like a straight person looking around the room to "see" if there are any gay people.) You should assume that there may be transgender people at any gathering.
If you're unsure which pronoun a person prefers, listen first to the pronoun other people use when referring to that person. Someone who knows the person well will probably use the correct pronoun. If you must ask which pronoun the person prefers, start with your own. For example, "Hi, I'm Dani and I prefer the pronouns she and her. What about you?" Then use that person's preferred pronoun and encourage others to do so. If you accidently use the wrong pronoun, apologize quickly and sincerely, then move on. The bigger deal you make out of the situation, the more uncomfortable it is for everyone.