Many LGBTQ+ people use labels to express who they are. These labels can help listeners like you and me understand who that person is and how they wish to identify. Some labels are often used universally by LGBTQ+ people, while others relate to the following concepts specifically:
Gender Expression (GE). The external manifestations of gender, expressed through such things as names, pronouns, clothing, haircuts, behavior, voice, body characteristics, and more.
Gender Identity (GI). One’s internal, deeply held sense of gender. Some people identify completely with the gender they were assigned at birth (usually male or female), while others may identify with only a part of that gender, or not at all. Some people identify with another gender entirely. Unlike gender expression, gender identity is not visible to others.
Sex (S). At birth, infants are commonly assigned a sex. This is usually based on the appearance of their external anatomy, and is often confused with gender. However, a person’s sex is actually a combination of bodily characteristics including chromosomes, hormones, internal and external reproductive organs, and secondary sex characteristics. As a result, there are many more sexes than just male and female, just like there are many more genders than just male and female, as well.
Sexual Orientation (SO). The desire one has for emotional, romantic, and/or sexual relationships with others based on their gender expression, gender identity, and/or sex. Many people choose to label their sexual orientation, while others do not.
(Source: It Gets Better Project which envisions a world where all LGBTQ+ youth are free to live equally and know their worthiness and power as individuals.)