The hyphen is often confused with en dashes and em dashes. Many of the writers we work with use the hyphen as en dashes and as em dashes. However, hyphens, en dashes, and em dashes are different punctuation marks.

The hyphen is used to join two words into a single word (well-being).  The use of hyphens to connect compound words is declining, and a good rule to go by is to only use a hyphen is the sentence would be confusing without it.

For example: I have three hundred year old trees in my yard.  This is confusing. Do I have three trees that are hundred years old or do I have an unspecified number of three hundred year old trees? The hyphen helps clarify: I have three hundred-year old trees in my yard.

En dashes are a little longer than a hyphen. They are usually used to indicate ranges, and are easily replaced by the word to.

For example:

This facility is for children from 5-12 years old.

This flower blooms from June–September.

The en dash can also be used to connect compound adjectives in which one part consists of two words or a hyphenated word.

For example: The post–9-11 era

An em dash is wider than the en dash. It replaces commas, semicolons, colons, and parentheses to indicate added emphasis or—like this—to set of a comment.

For example:

Pete—my sweeper boy—is awesome.

Never have I met a truly annoying person—until I met my husband.

I recommend using no spaces before or after en or em dashes.

The other day, my husband and I were driving behind a truck with the phrase “Womens Clothing.” My husband rolled his eyes as I pointed out the error, but this is a common mistake. So here’s to clearing the confusion.

Plural nouns are easy: I have three cats and five dogs.

Singular possessive nouns are also easy: This is my sister’s dress.

Now, plural possessive nouns. If they end in an s, add only a apostrophe: Dogs’ favorite activity is going for walks.

If they don’t end in an s, add an apostrophe and s: Women’s clothing.

People _____ are vegetarians are awesome runners. (For the sake of the example, overlook for a moment the fact that we could make this sentence more concise by saying “vegetarians are awesome runners.” See the tip on less is more.) What would you fill in here? Who or That?

Here, you should use “who” because you are referring to people. “That” is not per se incorrect, but I think it’s a good rule to keep who for people and persons.

How about this one: My husband is someone _____ excels at thinking up annoying moves, and then naming them.

In this case, who is the only choice. That is simply wrong here.

Use that for inanimate objects. For example, I want a dress that compliments my figure.

Following that rule (who for people and persons, that for inanimate objects), you should not use who and whom when referring to agencies, companies, organizations or other bodies.

For example: ‘Preissl Sweeper Services is a company that employs a lovely sweeper boy who goes by the name Pete.”

I see the phrase centre around fairly often, but it is non-sensical! You can centre on, not centre around. This phrase is an erroneous mix of the phrase revolve around and centre on.

John B. Bremner in his Words on Words warns:

It is physically impossible to center around. Make it center on. If you want to use around, use it with cluster, hover, revolve, rotate. Use around with circle when the context is dynamic (’The protesters continuously circled around the stadium’), but not when the context is static (’Police circled the hijacked plane’).

On Yahoo Questions, someone posts: I’ve been searching for romance novels that center around two women falling in love instead of man and woman.

No, these novels don’t centre around this theme. They centre, or focus on it. Please, stop centering around.