You’re probably used to hearing the term “LGBT,” but “LGBTI” might be new to you.

Nearly one in every 2,000 people is born with variations in reproductive or sexual anatomy, or has a chromosome pattern that doesn’t fit with what is typically considered male or female. Such individuals are “intersex” — the “I” in LGBTI — and can identify as male, female or neither. Along with lesbian, gay, bisexual and transgender people, intersex people are struggling in many places for recognition, equality and their human rights.

Being intersex is not as rare as you might think, but it is a condition invisible to outsiders, and some people do not discover they are intersex until they reach puberty.

Because intersex people are born with unique biological characteristics, they are different from transgender people, who do not identify with their assigned gender identity. Ironically, many intersex people receive unwanted surgeries and hormone treatments that transgender people have to fight for.

You can learn more about intersex people and the social challenges they face from support groups such as the Intersex Society of North America and InterACT Youth.