Through an imperative sentence, a speaker requests, commands, or issues a desire or wish for the listener to take an action. Normally, the sentence is short and punctuated by a period.
Imperative sentences are used to sell products---"Get back to sleep," for example, for a sleeping aid. They are also used for bumper sticker slogans, such as "Spread the Joy" or "Just Do It."
"Wash the car," "Go to the store" and "Pay the bill" are imperative sentences.