There are four ‘types’ of sentences. These describe what the sentence is doing, what it’s function is. All sentences are one of these four types:
Declarative sentences. Declaratives are statements; they are claims about the world or something in or connected to existence, e.g.
That crocodile has a taste for human flesh.
Love overcomes all, apart from crocodiles.
Interrogative sentences. Interrogatives are questions (‘interrogate’ = to ask questions, to get information), e.g.
Really?
Why did my parents tell me that love conquers all?
Imperative sentences. Imperatives are commands or instructions, e.g.
Don’t eat me!
Chew! or At least chew forty times before you swallow!
Exclamative sentences. Exclamatives are exclamations or interjections, short utterances that convey strong meaning, including happiness, surprise, fear, horror, disgust, etc, e.g.
No!
Guts!