Sexist language is language which excludes one sex or the other, or which suggests that one sex is superior to the other. For example, traditionally, he, him and his were used to refer to both sexes, male and female, but nowadays many people feel that this makes she, her and hers seem less important or inferior. It is best to avoid sexist language in order not to offend people.
He, she, him, her, his, hers
In writing, we can use (s)he, he/she, him/her or his/her to refer to both sexes at the same time. When speaking formally, we say he or she and his or her:
The teacher is the person who organises the class. (S)he is the one who controls timekeeping and the sequence of events.
Not: She is the one … or He is the one …
A police officer should remember that he/she is a public servant and should therefore always be polite. It is his/her duty to assist the public.
University administrator: Could each candidate please leave his or her exam registration form at the office before midday, please? (spoken)
We can use they, them, their and theirs to refer to both sexes at the same time, even when a singular noun has been used, although some people consider this unacceptable. However, in present-day English, this usage is becoming more accepted:
Every student must show their identity card on entering the examination room. (preferred to Every student must show his identity card.)
A nurse has to be very open and understanding. They must listen to their patients and respond to them. (preferred to She must listen to her patients. or He must listen to his patients.)