Exclamation mark (exclamation point) - a terminal point used to express strong feelings or to show emphasis.
Be careful with exclamation marks.
They can be fun, but they can also reveal a lack of composure, restraint, and confidence in letting words speak for themselves.
In other words, don't overuse them.
In a forceful question an exclamation mark replaces the question mark. The two terminal points can be combined, but this is not recommended.
Possible
Why haven't you cleaned your room?!
Preferred
Why haven't you cleaned your room!
If a sentence includes a quotation that ends with an exclamation mark, the comma that would usually be placed at the end of the quotation is not needed.
Incorrect
"How dare you!," she cried.
Correct
"How dare you!" she cried.
If a sentence includes a text title that ends with an exclamation mark, a comma should still be used to separate clauses within the sentence if needed.
Incorrect
One of my favourite comedies is Airplane! which was renamed Flying High! in Australia.
Correct
One of my favourite comedies is Airplane!, which was renamed Flying High! in Australia.
To express surprise or amusement at something we are reporting on we can add one or more exclamation marks in brackets.
However, this should be avoided in formal writing.
Example
She claims to have stayed awake for 72 (!) hours.