"Whom" is a pronoun used to refer to the object of a verb or preposition in a sentence. It is often used in formal contexts and is the objective case of "who." For example, in the sentence "To whom should I address the letter?" the word "whom" indicates the person receiving the action. In everyday conversation, many people use "who" instead of "whom," which can lead to confusion. However, "whom" is still important in writing and formal speech, especially when referring to people in a more precise manner. Understanding when to use "whom" can enhance clarity in communication.