Way back in the 14th century, there was something known as the “note of admiration.” Although it sounded very poetic, the usage was a bit limited, and the punctuation mark evolved into something more pragmatic. The contemporary name is the (oft-overused) exclamation point.
Just like candy at the movie theater, it’s all too easy to overindulge in exclamation marks. Take a look at your Twitter feed and you could put together a strong case for how they are overused. The more exclamation points you see, the less powerful the effect.
A better question than when to use an exclamation point might be when not to use this punctuation mark.
The crime of using a gratuitous number of exclamation points is easy to spot. A few guidelines: If something is serious, then an exclamation is not appropriate. If you're attempting to convey a level of experience and authority, no exclamation points. If you've already used one (or more), cut it out.
Sea levels have risen more than two meters, submerging Miami into the Atlantic Ocean.
This sentence delivers a more somber message than:
Sea levels have risen more than two meters, submerging Miami into the Atlantic Ocean!
Don't Go Overboard!
In general, exclamation marks should be used sparingly. Words are far more powerful than punctuation. Rather than an exclamation point, use "frenzy," "furor," or "flurry" to convey excitement. Or "exigency," "importunity," or "imminence" to relay urgency.
One carefully placed exclamation point can be impactful, especially if used in a case of shock. However, more often than not, it's better to avoid a misplaced one.
If you are doing any sort of formal writing, including work emails, dissertation papers, job applications, or letters to the editor, it’s probably best to avoid them all together.
But we're not complete exclamation curmudgeons. The one free pass to get maximum effect out of an exclamation mark is to use it with an actual exclamation. That means "Wow!," "Ouch!," "Hey!," and "No!" are all fair play.