"What" is a pronoun used to ask about a specific thing, person, or situation. In English, it is often used to start a question, such as "What is your name?" or "What time is it?" It can also be used as part of a statement, such as "I don't know what you're talking about." Additionally, "what" can be used as an exclamation to express surprise or disbelief, such as "What a beautiful sunset!" or "What a ridiculous idea!"