An interjection is a word or short phrase that indicates some sort of emotion. They are common in conversation but are used sparingly in formal writing, if at all. Some common interjections are ouch, wow, dear, uh, oh, ooh, well, hi, ah and hey.
Depending on where they are and what punctuation is used, they can convey a variety of emotions with a potency that ranges from milk to acid. A quiet, mild interjection may be attached with a comma to another sentence.
“My goodness, it’s cold out here.”
“Wow, you own more than one hat.”
“Ah, now I understand that conversation.”
When it stands alone with its own punctuation, it calls more attention to itself and is therefore more powerful. Alone, it can also indicate sarcasm.
“I get to fix a flat tire today. Yay.”
“Wow. Terry ate all of my cheesy dogs.”
“Hey. Get out of my chair.”
For greatest emotion, exclamation marks are added.
“I get to go to the zoo today! Yay!”
“Wow, Terry ate all of my cheesy dogs!”
“Hey! Get out of my potato chips!”
In this day of creativity, nearly anything can be yelled out in a fit of emotion, and some people make exclamations up as they need them. Rarely do these relate in any way to what the speaker is having a conniption fit over.
“Burger and fries! You wrecked my car!”
“Holy pepperoni, that is hot!”
“Sweet mother of collie puppies, what did you do to the bathroom!”