October 26 is Intersex Awareness Day. While there are some important distinctions between intersex individuals and members of the LGBT community (more on that below), we have a long history of working together as allies.

In the spirit of continuing that relationship, here are seven things you should know to be a good ally to an intersex friend.

What does "intersex" mean, anyway?

Intersex is a blanket term referring to people who are born with sex characteristics that fall outside the traditional notions of male and female bodies. Sometimes the differences are physical, other times chromosomal. For example, an intersex person may be born with XY chromosomes and testes, with XY chromosomes and ovaries, or even with an extra chromosome (XXY).

There are over 30 types of intersex variations, which may be related to chromosomes, hormone levels, genitals, and/or internal reproductive organs. Intersex traits are not necessarily life-threatening, but some may be associated with serious medical conditions. (That's the intersex flag above, by the way.)

It's important to understand that intersex refers to biology rather than identity. While "gay," "lesbian," and "bisexual" refer to sexuality, and terms like "transgender" and "genderfluid" refer to gender identity, intersex refers specifically to physiological traits.

Some people don't discover they're intersex until later in life.

Some intersex characteristics, like those that affect the appearance of a person's genitals, are identified at birth. Others, like those affecting hormone levels, may not be discovered until puberty, when secondary sex characteristics like hair growth, body odor, breasts and/or menstruation fail to develop. (Model Hanne Gaby Odiele, above, found out she was intersex when she was 17.)

Some don't find out until even later in life—people can discover that they're intersex at any age.

Being intersex is a lot more common than you think.

Experts estimate that up to 1.7% of the world's population is born with intersex traits. THat's about the same as the percentage of people born with red hair.

So it's likely you've met someone who is intersex, even if you didn't realize it.

Genital surgery on intersex babies is still common.

October 26th is celebrated as Intersex Awareness Day because it's the anniversary of the first public demonstration by intersex people in North America in 1996. Advocates gathered outside the American Academy of Pediatrics's annual conference on Boston to protest the organization's support for cosmetic genital surgery on intersex babies.

That fight continues 21 years later: Despite numerous studies indicating infant genitoplasty does more harm than good, physicians in the U.S. and elsewhere still routinely perform medically unnecessary procedures on intersex babies.

Parents consenting to these operations usually have the best of intentions. But these procedures, which are almost always irreversible, can leave patients sterile, interfere with urination, and affect a person's sexual function and sensation. Some people operated on as babies report feeling they were assigned the wrong sex, and even those who do feel at home in their bodies often show high levels of psychological distress when they learn they were operated on as infants.

Doctors argue these procedures are necessary to prevent stigma and psychological trauma, but a long-term study in the International Journal of Pediatric Endocrinology indicated intersex children who were not operated on showed “no major concerns."

Intersex activists, international human rights organizations, and even several former U.S. Surgeons General regard this as a critical human rights issue. They're urging pediatricians to delay medically unnecessary surgery and instead let intersex kids grow up with whatever healthy genital tissue they're born with, so they can make the decision for themselves when they're older.

There's a long history of discrimination against intersex athletes.

International sports has a long history of subjecting female athletes to sex testing: As recently as the 1960s, Olympic athletes were forced to strip naked before doctors before to receive a "certificate of femininity," which they'd then have to carry with them to prove their womanhood.

Intersex athletes continue to face discrimination today. South African runner Caster Semenya is perhaps the most famous: In 2009, the International Association of Athletics Federations (IAAF) forced Semenya to undergo gender testing. Results revealing that she had hyperandrogenism, which causes elevated testosterone levels, were leaked to the press and she was hounded mercilessly on social media. the IAAF made special rules requiring intersex athletes to either undergo hormone replacement therapy or have surgery to regulate their testosterone levels.

Thankfully, the rules were suspended in time for Semenya to take home the gold in the women's 800-meter race in the 2016 Olympics last year. But the IAAF could still reinstate them.

The intersex community's moment of visibility is long overdue.

Intersex people (and their parents) have long been told by doctors to keep keep their status a secret. In some parts of the world, child abandonment, infanticide and violence against the mothers of intersex children is common.

But now, more and more intersex people are coming out to share their stories are erase the stigma.

Earlier this year, Belgian model Hanne Gaby Odiele came out as intersex. So did Dutch singer Elle Bandita. Intersex activist Hilda Viloria has published a memoir exploring a life lived between genders, and in April, intersex activists from all over the world gathered in Amsterdam for the largest International Intersex Forum ever.

Intersex people are gaining more visibility in popular culture and the media, too: MTV's Faking It introduced an intersex character in 2014, and later featured guest actor Amanda Saenz, the first out intersex actor to play an intersex character on TV. A wide range of media outlets, from the the Washington Post and the Atlantic to Vogue, have begun highlighting the stories of intersex people.

Public policy in the U.S. is already starting to change: The first intersex birth certificate in the U.S. was issued in New York earlier this year and, last week, California followed Oregon to become the second state to legally recognize a third non-binary gender. (Montana is considering a similar change.)

You can help.

There are lots of ways to be an ally to the intersex community. You can donate to advocacy organizations like InterAct or the Intersex Campaign for Equality. You can educate your friends and family about intersex people by sharing their stories and educational resources on social media.

You can encourage others to treat intersex people respectfully by using their preferred pronouns and not asking invasive questions about their medical history.

You can also support nondiscrimination ordinances that specifically include intersex people, oppose anti-trans bathroom bills (which also impact intersex people), and support efforts to stop unnecessary procedures on intersex infants.