Why Should We Care Which One to Choose?
In writing academically or speaking formally, it is important to choose your words in a way that you don’t distinguish between genders or include both genders equally.
Nowadays, some people might find the gender-discrimination very offensive.
Singular 'they' is used instead of 'he' or 'she' to refer to a person whose sex is not mentioned or is unknown.
People who do not identify themselves as either male or female (non-binary people) usually prefer to be referred to as they.
In English, in the third person singular pronouns (he, she, his, hers, etc.) the gender is expressed explicitly. There are no personal pronouns that can refer to someone without identifying whether that person is male or female.
Why the Singular They?
That is why, in modern English, they have created a new pronoun called the singular 'they'. In the past, 'he' was used to refer to both men and women.
In modern English, this sentence is unacceptable. Instead, singular 'they' is used.
Other Ways to Avoid Gender Discretion
Some people prefer to use he or she instead of 'they' in speech and writing:
Other Alternatives for Gender Neutrality
Another alternative for avoiding gender specificity is writing He/she or (s)he. But all these variations are a bit frowned upon. And your best choice is to use 'they'.
It is better to try to change the sentence, using the singular 'they'.
With 'they' you can also refer to people in general, despite their gender.
Singular or Plural Verb?
When 'they' is the subject of a sentence, whether it is the singular 'they' or plural 'they', you must use plural verbs. Never say or write 'they
is'. Always use 'are' with this pronoun.