Gender-neutral
“They” is a gender-neutral third-person pronoun that can be used to refer to someone whose gender is unknown or not important. For example, “Somebody left their umbrella in the office. Could you please let them know where they can get it?”
Nonbinary
“They” can also be used as a nonbinary pronoun to refer to someone whose gender is known or knowable, but who does not identify as male or female. For example, “This is my friend, Jay. I met them at work”.
History
“They” has been used as a singular pronoun since at least the 1300s, appearing in the works of Geoffrey Chaucer, William Shakespeare, and Emily Dickinson.
Acceptance
“They” is now widely used in spoken English and is officially recognized as correct by several key bodies, including the American Psychological Association (APA), the Modern Language Association (MLA), and the Oxford English Dictionary.
Usage
It is important to always use a person’s self-identified pronoun, including when a person uses the singular “they” as their pronoun.