He/him; she/her; they/them. That's just the brink of the exploration of pronoun identification. There's a whole other area of pronouns that people use to define who they are and how they identify, which is also important to know and further explore.
The wonder of today is the ability to explore who you are and how you want to be seen. There is so much more acceptance and education around sexuality and gender identification, a space to be open and "out", and even just curious.
Nonbinary gender identification isn't a new idea. "Two Spirit" refers to the Native American idea of a third gender, that which is nondescript, and has been celebrated for decades. However, it wasn't until the 1980's that American culture became more aware of gender fluidity. And more recently, nonbinary seems to have become more of a movement towards acceptance across a wide range of personal explorations.
The fluidity of gender in our current day and age is something that is often debated based on society as a whole being able to adapt to both understanding and accommodating the change of pronouns each individual is wanting to be identified as. Divisiveness around fluidity and acceptance stems from both ends. Some people struggle with working out the preferred pronoun from what their eyes see, or the history with a person knows. Often, they will continue to refer to someone with gender specific pronouns opposite of the preferred pronoun even with much reminding. Here, it is important to appreciate, especially with teens, that self exploration takes on many different "hats" and healthy development comes from an openness to allow for such exploration. It is important, as a parent, teacher or adult mentor, that we be aware and accommodating to how adolescents are working out who they are and how they best feel comfortable in their bodies. Within the community at large, inclusivity of all people: gender, race, ethnicity, LGBTQ - is imperative for the health of society. We often judge what we don't know, so ask. Be curious and open to healthy conversations around gender identity and body awareness.
There is so much to learn and appreciate around this experience. To encourage conversation and exploration when you find yourself in situations where you have an opportunity to learn or teach will only help create a connectedness and understanding.