Everyone might not agree with me on this point, but I believe there is a much wider range of different "sexualities" than we usually suppose.
First there is someone's sexual orientation - what "type" of person you are physically attracted to. This is often what we think of when we talk of someone's sexuality, and it is often broken into only three categories: straight (attracted to someone of the opposite sex), homosexual/gay/lesbian (attracted to someone of the same sex), and bisexual (attracted to both sexes).
The problem with these three categories is that neglects to consider the true spectrum of genders/sexes that exist within humans (see
this previous post for more on that topic). There are people who are not male or female, and still others who identify as both male and female, and the above three categories assumes that no one would be attracted to someone who does not have a clear sex/gender label one way or the other.
To rectify this problem, new terms have developed (or been reclaimed) in recent years, including pansexual, omnisexual, and queer, which refer to being attracted to people of all genders, including transgendered individuals.
But this still doesn't cover the entirety of the human sexuality experience. What about people who bristle at the idea of labeling what gender/sex they are attracted to? After all, it's not like straight women are attracted to all men, or straight men are attracted to all women, or gay men are attracted to all men, or pansexuals are attracted to every single person on the planet. We are attracted to and forge connections with individuals, not entire genders. Or what about people who aren't attracted to anyone, and have a very low or non-existence sex drive?
These people are often glossed over when we talk of sexuality - but there is a vocabulary out there that's being increasingly used, in an effort to include them. There's demisexual, meaning that someone doesn't experience primary physical attraction, but may experience secondary attraction after forming a close personal bond with another person. There is also asexuality, a term for people who don't find themselves sexually attracted to anyone. (Asexual individuals often do form close bonds with people, and might even have (non-pleasurable) sex with them - but that is a choice, and has to do with sexual behaviors - which I'll get into more in a bit.) Gray-asexuality is another recent term, used to describe someone who feels their sexuality falls somewhere on a spectrum between sexual attraction and complete asexuality.
Keep in mind that these terms are not mutually exclusive. Someone could have a low libido and little interest in sex and therefore identify as asexual or gray-asexual or demisexual - but also identify as a specific sexual orientation (i.e. gay) because of who they are attracted to (i.e. someone of their same sex) on those rare occasions when they have sexual desire. Still others might have so few experiences of attraction or desire to draw from that they aren't sure how to label their orientation - or if they should label it at all.
Besides this, there are other things that might complicate someone's sexual orientation. For one thing, we all define attraction and desire a little differently - including or excluding physical attraction and emotional attraction depending on the person. For another, most of us are capable of understanding if someone could be considered "attractive" - even if they are not a gender we typically look at or would say we are personally attracted to.
I feel like women especially have this tendency to recognize (or appreciate, or feel threatened by) attractiveness/beauty/sexiness in people of any gender - because our world is built for a male gaze, and billboards and magazine covers and television ads and porn sites are plastered with still images and videos of attractive women; and because women are culturally taught to look at other women and judge themselves against each other; and because women are expected to make themselves more attractive to men (or to other women) by the way they dress, wear their hair, do their makeup, etc. This sort of environment can breed jealousy and envy, and I feel like there is often only a fine line between coveting someone's body because you want to have sex with them and coveting someone's body because you want your body to look like theirs.
This might transition into identifying as bisexual or pansexual for some women; for others, it would never. Close friendships between two people can also complicate things - particularly among those who form emotional bonds first and foremost, and rely on that emotional intimacy to lead them into physical/sexual attraction.
Finally, there are behaviors and choices to consider, which are other important parts of sexuality. These categories would include someone's past sexual experience and someone's future sexual experience - what they have done, and what they will choose to engage or not engage in in the future.
Celibacy is refraining from sexual behaviors of any kind, usually born from a desire to prioritize other areas of life instead (such as one's psychology or spirituality). Abstinence is choosing to refrain from sexual intercourse (though not necessarily other sexual behaviors) - often for religious/spiritual reasons or for medical reasons.
On the other end of the frequency spectrum are people who choose to have a lot of sex or engage in a wide range of sexual behaviors, perhaps with many different partners. There are plenty of terms used to describe such behavior - and many of them are gendered, because our society tends to view women and men differently in this regard. Women with multiple partners are "sluts" or promiscuous; men are "lucky" or "studs." These terms stem from the dual stereotypes that women don't or shouldn't want to have sex often, and if she does, something is wrong with her; and that men do or should want to have sex often, and if he doesn't something is wrong with him. Both of these are cultural bullshit. Some men don't want sex. Some women do. Every person is different (and can furthermore change from day to day), and gender stereotypes like these are both ridiculous and dangerous.
There are still other terms to describe how we form relationships (or how many relationships we form). Monogamy is the practice of forming a one-on-one connection with someone (sexual or otherwise), and not forming similar connections with anyone else simultaneously. Most marriages in the U.S. are monogamous - there are only two people in the marriage, and these two people have vowed to be in a closed, exclusive relationship with each other and no one else.
Open relationships, on the other hand, allow for multiple simultaneous relationships. Participants are often still in a core relationship they can rely on, with other additional experiences being only periphery, usually to fulfill specific needs that that person is not receiving from their core relationship. These could be physical needs (i.e. because their core partner is physically or emotionally unable to provide them with sexual pleasure or reproductive success), or emotional/romantic needs. For an open relationship to be successful and not breed resentment or confusion, it's important to set up specific agreements beforehand, and to keep lines of communication open throughout the experience.
Polyamory is the state of being in love with or romantically involved with more than one person at the same time. Often, polyamorous individuals find others who wish to structure their relationships in a similar way, and may even form bonds of more than two people - committed triads, quads, or complex networks of five or more people. This is different from an open relationship or open marriage in that there is not one "core partner" and then other "side partners"; instead of hierarchy, there is community. These bonded groups act as a family, and everyone in the family is as committed to each other as a monogamous long-term couple are to each other.
Those who never have sex are just as important as those who have sex every day; those who are attracted to or desire no one are just as important as those who find themselves attracted to people of all genders. All of these types of individuals should be included in conversations about the different types of sexuality found in humans.
And that's what I mean by the "Sexuality Umbrella" - sexuality encompasses more than just your sexual orientation. It also includes your frequency of sexual attraction or desire, your experiences, and your behaviors.
With so many things to consider, it might seem the height of uselessness to bother with any of these labels at all. If their definitions are so murky, and have the ability to change over time, why even bother? But the truth is, labels can help people define their experiences both for themselves and for the benefit of others. The human brain is hardwired to categorize things and people, and making these sorts of categories helps many of us better understand our world and our place in it. Deciding what to label themselves or even inventing new labels is a wonderful liberating experience, a key part of their journey through self-discovery, and a crucial part of their journey to find (a) partner(s) to spend their lives with (or part of their lives with, or one night with). Why would anyone discourage someone from doing what they need to find happiness?
Indeed, the nihilistic "why even bother?" attitude is often perpetuated by well-meaning but ultimately ill-informed heterosexuals. It's the same idea as asking, "Why can't we all just be 'color-blind'? Why do we have to categorize race at all?" It's easy to say when you already fit the label that's used as society's default (i.e. heterosexual and white) because if all subcategories ceased to exist and we were all considered just one type of sexuality or just one race, that person's identity (heterosexual and white) would still remain - it's all the others that would get erased. Acknowledging them is to validate them; to ignore those labels or pretend that they do not matter is to invalidate those labels and therefore also the people who use them to describe their experiences - which is something I would never want to do.
