Transequality is an organization that is dedicated to educating about & supporting advocacy for transgender people.  This FAQ provides clear definitions, addresses common misperceptions and offers suggestions and advice to promote awareness and inclusivity. 

Excerpt from site: 

Transgender people come from every region of the United States and around the world, from every racial and ethnic background, and from every faith community. Transgender people are your classmates, your coworkers, your neighbors, and your friends. With approximately 1.4 million transgender adults in the United States—and millions more around the world—chances are that you've met a transgender person, even if you don't know it.

What does it mean to be transgender?

Transgender people are people whose gender identity is different from the gender they were thought to be at birth. “Trans” is often used as shorthand for transgender.

When we're born, a doctor usually says that we're male or female based on what our bodies look like. Most people who were labeled male at birth turn out to actually identify as men, and most people who were labeled female at birth grow up to be women. But some people's gender identity – their innate knowledge of who they are – is different from what was initially expected when they were born. Most of these people describe themselves as transgender.

A transgender woman lives as a woman today, but was thought to be male when she was born. A transgender man lives as a man today, but was thought to be female when he was born. Some transgender people identify as neither male nor female, or as a combination of male and female. There are a variety of terms that people who aren't entirely male or entirely female use to describe their gender identity, like non-binary or genderqueer.

Everyone—transgender or not—has a gender identity. Most people never think about what their gender identity is because it matches their sex at birth.

This is a brief overview of the political and social issues (and perceptions) regarding bathroom access and the transgender community. 

Excerpt from Transequality.org: 

Bathroom access for transgender people has recently become a focal point of conversation and debate. This page includes information for transgender people and allies on responding to various questions and concerns regarding bathroom access.

If you need more information on what it means to be transgender, visit Frequently Asked Questions about Transgender People. For more information on how to be supportive of transgender people, visit Supporting the Transgender People in Your Life: A Guide to Being a Good Ally.

Tips for Allies of Transgender People: 

The following are tips that can be used as you move toward becoming a better ally to transgender people. Of course, this list is not exhaustive and cannot include all the "right" things to do or say because often there is no one "right" answer to every situation you might encounter.

When you become an ally of transgender people, your actions will help change the culture, making society a better, safer place for transgender people - and for all people (trans or not) who do not conform to conventional gender expectations

This link is to GLADD (Gay & Lesbian Alliance Against Defamation) - and offers clear, concise information about transgender people, definitions of terms, information about the transition process and how to promote & contribute to tolerance, safety andr respect.  or respect.

Excerpt from GLAAD's FAQ re: Transgender People: 

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.