Hyphens are one of those argument-inducing areas of the English language that has vocal parties on either side of any issue. Is the glass half full or is it half-full? Do we go over the proposal with a fine-tooth comb, or with a fine tooth-comb? (Or is it a finetooth comb?) Any set or rules, even ones that are discussed in a formal style manual, will likely end up being refuted in another style manual of equal clout.

Rules & Guidelines for Hyphens

The fact is, there's really no set of hyphen rules on which every person can agree. Following are a few of the more common rules, and some guidelines to follow when deciding yourself whether or not to use a hyphen.

Before a Noun

A hyphen should be used in order to create an adjective if the phrase comes before the noun in a sentence. However, the hyphen should not be used if the phrase follows the noun in the sentence.

A well-respected CEO gets a hyphen, whereas a CEO who is well respected does not.
A widely-known author is a hyphenated author, but an author who is widely known gets no hyphen at all.

This is the most common rule of hyphenation, and among the most misunderstood, but nearly all authorities would agree on it.

Related Words

If two words are inextricably linked, you can choose to hyphenate them (or you may combine the words together). The hyphen is necessary if the words are not combined into a single compound word.

Book-case may properly be written as bookcase.
The prefix "anti" is sometimes used with or without a hyphen, as in anti-discrimination (or antidiscrimination).

There are, of course, exceptions to the rule:

Most prefixes, such as ex- and sometimes anti-, are used with hyphens instead of making the words compound.

When one of the words is a proper noun, always hyphenate. Un-American never becomes unAmerican; the hyphen is necessary to avoid confusion.

Avoiding Confusion

Hyphens can be useful to avoid confusion. For example:

"Tom pulled an issue off the dirty magazine-rack" has a dramatically different meaning than "Tom pulled an issue off the dirty-magazine rack."

"The baseball player re-signed his contract" is almost the exact opposite of "The baseball player resigned his contract." In this instance, the meaning of the sentence would be ambiguous, at best, without the addition of the hyphen.

Simply put, use your common sense.

Other Common Instances

Some nouns, such as attorney-at-law, require hyphens in order to make the noun look complete.

Compound numbers and fractions use hyphens all the time: three-fifths and twenty-five should contain hyphens.

Other compound words, especially when they appear before nouns in a sentence, will be hyphenated. These include such common phrases as:

on-the-fly
on-the-go
out-of-date

Hyphens are also used to break words apart between syllables at the end of a line.

If you're a stickler for hyphenation, it's best not to use spell-check, or to justify the words in the center of a page. The hyphens created by your computer will at best be awkward, and at worst completely incorrect. Let the computer leave hyphens to you, the hyphen expert.

Consult a Dictionary

This leads us to a final word. Compound words are tricky things, and the way they're written changes over time. Often, a compound word will start out as two words and then become a hyphenated phrase before it ultimately ends up as a true one-word compound.

The newest version of any dictionary of merit will help you to make the distinction. For example, in the instance of fine-tooth comb:

The most commonly accepted hyphenation occurs between "fine" and "tooth."

According to English novelist Sir Kingsley Amis, this commonly accepted form is incorrect: the expression, according to him, was originally "fine tooth-comb."

In this case, feel free to use whichever you prefer. In most cases, you'll simply want to follow your dictionary's instructions on matters of compound words.