who 
/ˈhu:/ pronoun
/ˈhu:/ pronoun 1 a : what or which person or people — used when you do not know the name or identity of a person or group of people that you are talking about or asking about ▪ Who will be the next president? ▪ Who is standing next to you in this photo? ▪ I didn't know who he was. ▪ Find out who they are. ▪ I wonder who else signed up. ▪ Who should walk in [=who do you think walked in] when we least expected it? My parents! ▪ She isn't sure who she talked to.
b — used to question a person's character or authority ▪ Who are they to tell us what to do? [=what makes them think they can tell us what to do?] ▪ Who do you think you are? [=what gives you the right to say or do this?] ▪ Who do you think you're talking to? [=what gives you the right to speak to me in this (rude) manner?]
c — used in questions that are meant to say that no one would or would not do something, know something, etc. ▪ They may come or not. Who cares? [=no one cares; I don't care] ▪ Of course I would love to win a million dollars. Who wouldn't? [=anyone would] ▪ “Are they coming?” “Who knows?” [=no one knows; I don't know] ▪ Who are we kidding? [=we aren't kidding/fooling anyone] usage whom 2 — used after a noun or pronoun to show which group of people you are talking about ▪ Subscribers who are interested in joining the discussion group should contact the secretary. ▪ The people who conducted the study were extremely professional. ▪ Someone who handles stress well will be more suited for the job. ▪ I have a friend who my parents don't like. 3 — used to introduce an additional statement about someone who has already been mentioned ▪ His patient, who was a well-known television personality, suffered a minor stroke. ▪ The former president of the company, who is retired now, is credited with expanding and improving the product line. ▪ Her uncle, who she's very fond of, lives next door.
b — used to question a person's character or authority ▪ Who are they to tell us what to do? [=what makes them think they can tell us what to do?] ▪ Who do you think you are? [=what gives you the right to say or do this?] ▪ Who do you think you're talking to? [=what gives you the right to speak to me in this (rude) manner?]
c — used in questions that are meant to say that no one would or would not do something, know something, etc. ▪ They may come or not. Who cares? [=no one cares; I don't care] ▪ Of course I would love to win a million dollars. Who wouldn't? [=anyone would] ▪ “Are they coming?” “Who knows?” [=no one knows; I don't know] ▪ Who are we kidding? [=we aren't kidding/fooling anyone] usage whom
who's who 1 or who is who : information about the people who make up a group
▪ We had lived in this town long enough to know who was who. [=to know the names of the different people, what they did, etc.] ▪ I'm still learning who's who around the office. 2 a : a list of the names of the important and well-known people in a particular field
▪ The guest list reads like a who's who of the publishing industry.
b : the important and well-known people in a particular field
▪ The convention was attended by a who's who of the publishing industry.
▪ We had lived in this town long enough to know who was who. [=to know the names of the different people, what they did, etc.] ▪ I'm still learning who's who around the office.
▪ The guest list reads like a who's who of the publishing industry.
b : the important and well-known people in a particular field
▪ The convention was attended by a who's who of the publishing industry.
