The phrases "who are you" and "who is you" have distinct differences in terms of their grammatical correctness and meaning.
- "Who are you": This is the correct and standard form of the question. It is used to ask about the identity or the personhood of someone. The pronoun "you" is the second-person singular or plural pronoun, and "are" is the present tense form of the verb "to be" that matches with "you." So, "who are you" is asking the person to reveal or confirm their identity.
Example: A: "Hi, I'm John. Who are you?" B: "I'm Sarah."
- "Who is you": This phrase is grammatically incorrect in standard English. The pronoun "you" is a second-person pronoun, and "is" is the present tense form of the verb "to be" that matches with the third-person singular pronouns like "he," "she," or "it." Since "you" is not a third-person pronoun, the phrase "who is you" doesn't make grammatical sense.
To ask about someone's identity, the correct question is "Who are you?" If you want to refer to the identity of another person, you would use "Who is he/she/it?" depending on the gender or number of the person or thing you are inquiring about.
Example: A: "I saw someone walking outside. Who is he?" B: "He's my neighbor."
In summary, "who are you" is the correct way to ask someone about their identity, while "who is you" is not grammatically correct and does not have a valid usage in standard English.