An imperative sentence gives a command. It usually end with a period, but it may also end with an exclamation point (!).
Commands ask or tell people to do something.
Both of those sentences are commands.
The first one doesn't sound as commanding as the second one, but both of them are commands because they both ask or tell someone to do something.
Here are some example sentences for you to check out. I've underlined the subjects for you.
Dog and Jimmy are the subjects of those sentences. They tell us whom or what the sentences are about.
Now, take a look at some imperative sentences.
What is the subject of those sentences? Hmm... that's tricky!
This may sound strange, but every single command has the same subject! Yikes! How is that even possible?
Well, since commands are always speaking to someone or something (you've got to address them if you're going to ask them to do something), the subject is always the word you.
You may have noticed that the word "you" is not even in a command. Because of this, the subject is actually called you understood, and it is written like this: (you)
This means that the subject is the word you, but since you is not written or spoken in the sentence, it is simply understood and is written in parentheses.
|Please find my yellow leotard.||(you)|
|Shut the door!||(you)|
|Be there at 5:00.||(you)|
When a command begins with a noun of direct address, you might get tricked into thinking that it is a declarative sentence.
Bob, shut the door!
Grandma, be there at 5:00
But, don't get tricked! These sentences are still commands and their subjects are still (you). Learn more about nouns of direct address beginning imperative sentences here.