Intersex is a description of anyone who has physical, hormonal or genetic traits that aren’t only male or only female. This is a natural variation of sex expression, not a health problem!
Intersex is the “I” in LGBTI, but it’s not a gender identity or sexuality. Intersex people can have the full range of gender identities (male, female, genderqueer etc) or sexual preferences (gay, lesbian, bisexual, queer, etc) like anyone else! Like LGBT people they have faced stigma and discrimination due to homophobia and simply existing outside of the male/female binary.
To learn more about how to be an ally of intersex people, check out these articles & videos over at Intersex Australia.