I'll admit it. I suck at certain aspects of grammar and punctuation. However, I'm continually striving to improve. After all, isn't that what a good writer does?
My latest quest had me seeking the answer on how to properly use the hyphen.
Hyphens are hold overs from the days of typewriters when a writer ran out of page, but not word. Following the good old dictionary's suggestion on where to split up words, a writer would insert the hyphen at the ap-pro-pri-ate point. Modern use of the hyphen typically denotes compound words (well-known...but only if it precedes the noun it modifies), numbers (twenty-one), certain prefixes (ex-husband), or a place holder for suspended compounds (not recommended because it leaves the audience wondering what the modified noun is until later in the sentence).
But the answer to my question was...I don't want to know how to use the hyphen, I want to know how to use the em dash--which to express using the computer keyboard is two hyphens.
Em dashes are used like parenthesis to present a clause related to a sentence element, but not necessarily to the sentence as a whole.
A side note: Apparently I have problems spelling as well since spell check informed me hyphen is spelled with an 'h' after the p. :)