vs
QUICK ANSWER
"A quién" is a phrase which is often translated as "to whom", and "de quién" is a phrase which is often translated as "whose". Learn more about the difference between "a quién" and "de quién" below.
a quién()
A phrase is a group of words commonly used together (e.g., once upon a time).
a. to whom
Si no sabe a quién dirigir la carta, llame y pregunte.If you don't know to whom you should address the letter, inquire about it over the phone.
de quién()
A phrase is a group of words commonly used together (e.g., once upon a time).
a. who
¿En nombre de quién habla usted?Who are you representing?
¿De parte de quién?Who shall I say is calling?
