There are four kinds of sentences:

Declarative sentence

A declarative sentence makes a statement.

Richard is feeding the hens.
The children are swimming.
The telephone rang.
Everyone sat down.

Interrogative sentence

An interrogative sentence asks a question.

What is Richard doing?
Where are the twins?
Are you going shopping today?
What is your name?

exclamatory sentence

An exclamatory sentence expresses strong emotion.

What lovely weather!
The silly girl!
How stupid I am!
This is awesome!

Imperative sentence

An imperative sentence gives an order.

Come back!
Please sit down.
Tell me the truth.
Speak up!