WHAT IS IT CALLED GRAMMATICALLY WHEN YOU TELL someone to do something called?

Grammatically, telling someone to do something is called an imperative sentence.

Here's why:

* Imperative means "giving a command or order".

* Sentences are groups of words that express a complete thought.

Therefore, an imperative sentence is a sentence that gives a command or order.

Example:

* "Close the door." (This is an imperative sentence because it tells someone to do something.)