According to Wikipedia?
Non-binary, or genderqueer, is a spectrum of gender identities that are not exclusively masculine or feminine—identities that are outside the gender binary.[1] Non-binary identities can fall under the transgender umbrella, since many non-binary people identify with a gender that is different from their assigned sex[2] but does not necessarily, as some intersex people are also non-binary.
Non-binary people may identify as having two or more genders (being bigender or trigender);[4][5] having no gender (agender, nongendered, genderless, genderfree or neutrois); moving between genders or having a fluctuating gender identity (genderfluid);[6] being third gender or other-gendered (a category that includes those who do not place a name to their gender).
Gender identity is separate from sexual or romantic orientation,[8] and non-binary people have a variety of sexual orientations, just as cisgender people do.
A non-binary gender is not associated with a specific gender expression, such as androgyny. Non-binary people as a group have a wide variety of gender expressions, and some may reject gender "identities" altogether.