An interjection is a word that expresses some kind of emotion. It can be used as filler. Interjections do not have a grammatical function in the sentence and are not related to the other parts of the sentence. If an interjection is omitted, the sentence still makes sense. It can stand alone.

Ouch! That hurts.
Well, I need a break.
Wow! What a beautiful dress!
When you are expressing a strong emotion, use an exclamation mark (!). A comma (,) can be used for a weaker emotion.

Interjections do the following:

1.Express a feeling—wow, gee, oops, darn, geez, oh:

Oops, I’m sorry. That was my mistake.
Geez! Do I need to do it again?
Oh, I didn’t know that.
2.Say yes or no—yes, no, nope:

Yes! I will do it!
No, I am not going to go there.
Nope. That’s not what I want.
3.Call attention—yo, hey:

Yo, will you throw the ball back?
Hey, I just wanted to talk to you about the previous incident.
4.Indicate a pause—well, um, hmm:

Well, what I meant was nothing like that.
Um, here is our proposal.
Hmm. You really need to be on a diet.