BizWritingTip reader: “I always believed that you should use who when you are referring to people and that when referring to things. However, these two words seem interchangeable now. What is correct?”
BizWritingTip response: A few reference books say you can use both words interchangeably. However, conventional thinking supports your understanding. Use who (and its related forms, whose and whom) to refer to people.
Anyone that wishes to attend should send his or her name to HR. ?She is a manager that I would like to work for.
Anyone who wishes to attend should send his or her name to HR. (Who refers to the individual.)
She is a manager whom I would like to work for.
Use that or which for non-human things. If the phrase following is essential to the meaning of the sentence, use “that.” If the phrase following is not essential, use “which” and surround the phrase with commas.
The report that I sent you last week answers your questions. (“That” refers to a thing, and the phrase “I sent you” is an essential phrase. )
The meeting, which was delayed for an hour, featured some interesting speakers. (“Which” refers to a thing, and the phrase “was delayed for an hour” is not essential to the meaning of the sentence.)
In many cases, the decision as to whether a phrase is essential or not is entirely subjective. In other words, the writer gets to choose the points he or she wants to emphasize.
I trust this is a BizWritingTip that will help you with your writing.