Non-Binary is a gender often put under the transgender umbrella. It is often disregarded and those who identify as non-binary are belittled. Non-Binary people do not identify as male or female. Some are more feminine or masculine but most present themselves pretty androgynous. They often use they/them pronouns.

Yes, we exist, someone who goes by They/Them pronouns, Non-binary is a blanket term for Genderfluid, Genderqueer, Questioning etc. We don't feel right in either binary gender pronouns (ie. She/Her He/Him) and if you don't understand that then that's ok I guess, but please be nice to us, we're sad

Someone who is neither/not wholly of the binary genders; perhaps somewhere in the middle, entirely outside, partly one or the other, both simulataneously, fluctuating, etc.

These all have proper names but non-binary is an umbrella term for these things.

Somebody who is NOT mentally ill, but somebody who doesn’t identify as cisgender (male or female). Somebody who is non binary may use they/them pronouns or neopronouns. A common stereotype is them saying “did you just assume my gender” unironically. This is an offensive stereotype and should not be used.

A person who identify's as male or female, someone who is valid. An umbrella term.
It isn't fake, THEY aren't doing it for attention, it is not a mental illness, we are not "special snowflakes", our pronouns are they/them, WE ARE VALID!!!! If you still don't understand, google it or something,

Non-binary people may also identify as transgender and/or transsexual. The label genderqueer has a lot of overlap with non-binary. Non-binary is often seen as the preferred term, as "queer" may be used as a transphobic insult.

Non-binary people may wish to transition so that their gender expression more closely reflects their internal identity. Many non-binary people wish to appear androgynous and adopt unisex names, gender-neutral titles such as Mx. and/or gender-neutral pronouns, but others prefer to express themselves in ways which are traditionally seen as masculine or feminine or to mix aspects of the two.

Non-binary people can have any sexual orientation, although if attracted primarily to a single gender they may prefer to use gender-terminology to express this, such as androsexual or gynosexual.

To not identify with any gender. They use pronouns most commonly they /them instead of he or she.