Oh! The joy of interjections! Interjections, words that express a burst of emotion, are not grammatically related to other elements in a sentence.
Hey! Look out! Oh, no! Bravo! Wow!
Curses are also interjections: Damn!
Interjections can add a sudden, emotional tone to writing if they are used judiciously. Although no rules apply to interjections, you should limit your use of them. The emotion and power of interjections will be diluted if they are used too often. Generally, although not always, exclamation marks immediately follow interjections.
Ouch! Hurrah! Mercy! Awesome! Help!