The Exclamation Mark

The
exclamation mark (!), known informally as a bang or a shriek, is used
at the end of a sentence or a short phrase which expresses very strong
feeling

Here are some examples:i
What a lovely view you have here!i
That's fantastic!i
Johnny, don't touch that!i
Help!i
Good heavens!i
Aaarrgh!i

Examples like these are
quite normal in those kinds of writing that try to represent ordinary
speech ‹ for example, in novels. But exclamation marks are usually out
of place in formal writing. Using them frequently will give your work a
breathless, almost childish, quality

An exclamation mark is also usual after an exclamation beginning with what or how:i
What fools people can be!i
How well Marshall bowled yesterday!i

You can also use an exclamation mark to show that a statement is very surprising:i
After months of careful work, the scientists finally opened the tomb. It was empty!i

It is also permissible to use an exclamation mark to draw attention to an interruption: i
On the (rare!) occasion when you use a Latin abbreviation, be sure to punctuate it properly

Otherwise, you should generally avoid using exclamation marks in your formal writing. Don't write things like this: i
Do not use exclamation marks in formal writing!i
In 1848, gold was discovered in California!i

Don't use an exclamation mark unless you're certain it's necessary ‹ and never use two or three of them in a row: i
This is a sensational result!!!i

This sort of thing is all right in personal letters, but it is completely out of place in formal writing

Summary of exclamation marks:i
Don't use an exclamation mark unless it's absolutely necessary
Use an exclamation mark after an exclamation, especially after one beginning with what or how

Source: [ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذا الرابط]