What does transgender mean?
Transgender is a term used to describe people whose gender identity differs from the sex they were assigned at birth. Gender identity is a person's internal, personal sense of being a man or a woman (or boy or girl.) For some people, their gender identity does not fit neatly into those two choices. 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 non-binary. Always use the term used by the person.
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 into alignment with their gender identity. This is called transition.
As part of the transition process, 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" or "Max is a transgender man." And transgender never needs an "-ed" at the end.