An interrogative sentence is a type of sentence that asks a question. It typically begins with a question word such as who, what, where, when, why, or how, or it may start with an auxiliary verb like is, are, can, or do. Interrogative sentences usually end with a question mark. These sentences are used to gather information or clarify details. For example, "What time is the meeting?" or "Can you help me?" are both interrogative sentences. They play a crucial role in communication by prompting responses and facilitating conversation.