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 making a polite request, words like "please" can be added, as in "Please sit down." In contrast, a more direct command might simply state, "Sit down." Overall, imperative sentences are essential for communication in everyday situations.