An imperative sentence is a type of sentence that gives a command, instruction, or request. It often starts with a verb and can be directed at one person or a group. For example, "Close the door" or "Please pass the salt" are both imperative sentences. They can end with a period or an exclamation mark, depending on the tone. Imperative sentences can also be polite or forceful. When using the word "please," the tone is more courteous, as in "Please sit down." In contrast, a direct command like "Sit down!" is more authoritative. Overall, imperative sentences are essential for effective communication in everyday situations.