The exclamation mark is used to at the end of an emphatic declaration, interjection, or command.
For example:
An exclamation mark may be used to close questions that are meant to convey extreme emotion, as in
An exclamation mark will often accompany mimetically produced sounds, as in
"All night long, the dogs woof! in my neighbor's yard"
If an exclamation mark is part of an italicized or underlined title, make sure that the exclamation mark is also italicized or underlined:
My favorite book is Oh, the Places You'll Go!
*Never add a period after such a sentence that ends with the title's exclamation mark.
You can also use it to mark a phrase as humourous, ironic or sarcastic.
1. What a lovely day! (when it obviously is not a lovely day)
2. That was clever! (when someone has done something stupid) Some general remarks:
1. Don't overuse the exclamation mark
2. Don't include a series of exclamation marks.
e.g. I'll never get it right!!!!