The acronym LGBTIQA stands for:
1) "L" - lesbians;
2) "G" - gays;
3) "B" - bisexuals;
4) "T" - transgender people;
5) "I" - intersex people;
6) "Q" - queer and questioning people;
7) "A" - asexual people and allies.
There are three different issues which are included into LGBTIQA spectrum:
1) sexual orientation;
2) gender identity;
3) intersex conditions.
1. Sexual orientation
It is romantic and sexual attraction to people of the opposite sex, of the same sex, or to both. It is commonly accepted that people may have one of the three sexual orientations:
1) heterosexual orientation (straight people) - attraction to the opposite sex;
2) homosexual orientation (gays and lesbians) - attraction to the same sex;
3) bisexual orientation - attraction to both sexes.
Some people have other sexual orientation, for example:
1) asexual orientation - attraction to neither sex;
2) pansexual orientation - attraction to all the sexes (including attraction to transgender and intersex people);
3) polysexual orientation - attraction to many sexes, but not to all.
People whose sexual orientation does not perfectly fit into straight, gay/lesbian, or bi sometimes consider themselves queer.
Many asexual people consider asexuality as the fourth sexual orientation - attraction to neither sex. However, asexual people are not a homogeneous group and there are many diversity among asexual people themselves. Some asexual people do not have any romantic and sexual attraction at all while some of them have only romantic relationships without sex. In this case, they may be romantically attracted to the opposite sex, the same sex, both sexes, and so on. So, in the case of asexual people, there is a difference between their sexual orientation and their romantic orientation.
1) aromantic: lack of romantic attraction towards anyone;
2) biromantic: romantic attraction towards males and females;
3) heteroromantic: romantic attraction towards person(s) of a different gender;
4) homoromantic: romantic attraction towards person(s) of the same gender;
5) panromantic: romantic attraction towards person(s) of every gender;
6) polyromantic: romantic attraction towards multiple, but not all, genders.
There are also other romantic orientations.
Besides asexual people (those who do not feel a need in sex with any other people) and sexual people (who have this need), there are also demisexual and some other people who are between them (they may act either way at different times or situations or have lower need for sex than sexual people).
2. Gender identity
It is how a person feels of themselves: whether he or she is a man, a woman, both, or neither. Here, there is a difference between sex and gender. Sex is biological, gender is psychological. Person's gender and gender identity are related. Gender identity may or may not match a person's biological sex. Thus, there are two main groups of people depending on their gender identities:
1) cisgender people - those whose gender identity and biological sex match one another;
2) transgender people - those whose gender identity and biological sex do not match one another.
Many transgender people identify themselves with the opposite sex. However, there are also genderqueer people who identify themselves as both men and women (bigender), as neither men nor women (agender), as a third gender, and so on.
Transgender people who have strong transgender feelings and feel strong discomfort of being of the wrong biological sex (gender dysphoria) are commonly known as transsexuals. They often pursue gender transition. Physical transition includes cross-sex hormone therapy and sex reassignment surgeries. Transsexuals who are biologically males, but psychologically females are called MTF (male-to-female) transsexuals or transwomen. Transsexuals who are biologically females, but psychologically males are called FTM (female-to-male) transsexuals or transmen.
Transgender people who have less strong feelings may feel comfortable with their biological sex and occasionally wear clothes of the opposite sex. These people are known as crossdressers (the word "transvestites" is usually considered by them as pejorative).
A person should be addressed according to their gender, not their sex. Thus, a transwoman (MTF transsexual) should be addressed as a woman and a transman (FTM transsexual) should be addressed as a man. It may be more complicated to address genderqueer people. It is better to avoid pronouns at all or to ask a genderqueer person how to address them.
Transgender and genderqueer people as well as cisgender people may have any sexual orientation. However, transgender people, especially transsexuals, attracted to the same biological sex may consider themselves straight while those attracted to the opposite biological sex my consider themselves gays/lesbians.
3. Intersex conditions
Some people have physical characteristics (primarily and/or secondary) of both sexes. These conditions may include: chromosome disorders, atypical genitalia or reproductive organs, overproduction or underproduction of sex-related hormones. There are around 100 different intersex conditions.
In the past, intersex conditions were classified according to intersex people's inner reproductive organs as:
1) "true hermaphroditism" (having both ovary (ovaries) and testicle(s) or gonads that are partially testicles and partially ovaries regardless of genitalia);
2) "male pseudohermaphroditism" (having only testicles and atypical or female-looking genitalia);
3) "female pseudohermaphroditism" (having only ovaries and atypical or male-looking genitalia).
This classification is considered outdated now. Intersex conditions include much more variations than "true hermaphroditism" and "pseudo-hermaphroditism." The word "hermaphrodite" is considered pejorative and incorrect.
Intersex people as well as non-intersex people may have any sexual orientation and gender identity. In many cases, they consider themselves ether men or women, though some of them consider themselves both or neither. Thus, a person may be intersex and consider themselves transgender or genderqueer at the same time.
Many intersex people undergo sex assignment surgery and/or hormone therapy in childhood in order to make them as close as possible to either men or women. However, in many cases, intersex people's gender identity does not match the sex they were made into. So, they often transition to another sex, passing through a similar process to transsexuals.
Intersex conditions are obviously biological issues. Although sexual orientation and gender identity are mainly psychological issues, there are evidences that they are caused by brain wiring. Transsexuals have brain structure of the sex they identify themselves with. Gays and lesbians have brain structure different from straight people. There are also hypotheses that sexual orientation and gender identity may depend on genetics. Thus, they probably have a biological basis.
Sexual orientation and gender identity are not a matter of choice and cannot be changed. It can be compared to being right- or left-handed. Whether a person is right- or left-handed is determined by the brain structure and is not a choice. In Western cultures, it is considered normal to be left-handed. However, in some cultures it is not so. In some cultures, left-handed children are taught to use right hand when they write, eat, and do other things. It sometimes causes a serious distress in children. After years of practice, they are able to do many things with their right hand, but it is still more natural for them to use their left hand and they are still unable to do some things with their right hand. When people who have non-straight sexual orientation or gender identity are taught to behave in the "proper" way, it causes even stronger distress and the results are even less satisfactory.