Singular they, along with its 
inflected or derivative forms, 
them, 
their, 
theirs, and 
themselves (also 
themself and 
theirself), is a 
gender-neutral third-person pronoun. It typically occurs with an indeterminate 
antecedent, in sentences such as:
"
Somebody left 
their umbrella in the office. Could you please let 
them know where 
they can get it?"
[1]
"My personal rule is to never trust 
anyone who says that 
they had a good time in high school."
[2]
"
The patient should be told at the outset how much 
they will be required to pay."
[3]
"But 
a journalist should not be forced to reveal 
their sources."
[3]
This use of singular 
they had emerged by the 14th century, about a century after the plural 
they.
[4][5][2] It has been commonly employed in everyday English ever since and has gained currency in official contexts. Singular 
they has been criticised since the mid-18th century by 
prescriptive commentators who consider it an error.
[6] Its continued use in modern 
standard English has become more common and formally accepted with the move toward 
gender-neutral language.
[7][8] Some early-21st-century 
style guides described it as 
colloquial and less appropriate in formal writing.
[9][10] However, by 2020, most style guides accepted the singular 
they as a 
personal pronoun.
[11][12][13][14]
In the early 21st century, use of singular 
they with known individuals emerged for people 
who do not exclusively identify as male or female, as ias in, for example, "This is my friend, 
Jay. I met 
them at work."
[15]