There are five types of English sentences, classified by their purpose:
Declarative sentence makes a statement, expresses opinion. It ends with a period “.”
Interrogative sentence expresses a question or a request in polite form. It uses a question mark “?”
Imperative sentence expresses a command, demand, request, direction or instruction. We can think of other functions, however, they all fall into one of those I listed above. For example, advice or invitation.
Join us on a 12-month journey to see them all. (invitation)
Check out the best post-holiday sales before you shop. (advice)
In addition, to summarize all the functions into one – it tells people what to do.
An imperative sentence ends with a period “.” or an exclamation point “!”
Exclamatory sentence expresses great emotion such as excitement, surprise, happiness, anger etc. It ends with an exclamation point “!”
A mixed type might be interrogative-exclamatory sentence ending with “?!”, “!?”, “?!?”, “!?!”
You paid what?!?
Hear this time it is the lower-down folks like analysts!?!
What is that noise?!
Workplace lunch dilemmas: Who pays!?
Why do we need to know this lesson? Because in English, each type has a specific word order. We need know in what order we must place the words to form a sentence. For learners of English this is important. Also, it helps to categorize punctuation signs and their application.