Knowledge of correct punctuation is vital for presenting well written and professional documents. There is often some confusion over how to correctly use the hyphen and dash marks in sentences. It is important to understand the differences:

The Hyphen ( - )

The hyphen is used in a number of ways:

It is often used when adding a prefix to certain words. This is usually done to make the word easier to read, such as in "re-examine"and "re-enter", but not all words follow this rule. For example, you would not hyphenate "undo" or "reorganize". When you do use a hyphen, however, the two words need to be dependent on each other, such as in "ex-wife", "re-edit". If in doubt, always check in your dictionary.

You need to use hyphens when you are creating compound words from separate words. Compound simply means to add things together. For example, "up-to-the-minute news", "over-the-hill pop stars".

Hyphens need to be used when you write numbers out as words, separating the two words of any numbers under one hundred with a hyphen: "thirty-eight cats", "twenty-three cars". For numbers over one hundred and where they are used as an adjective, it is fully hyphenated: "the two-hundredth anniversary". In other cases, the hyphen should only be used if a number over one hundred is present within a larger number: "The house is one hundred and fifty-five years old".

The Dash ( -- or - )

The Dash mark is used in a number of ways, not to be confused with the hyphen. There are two different types of dash, called "em" and "en".

Use an "em" dash when indicating a brief interruption in a statement or speech, a change of thought, adding a comment, to induce dramatic effect or to show a time frame not yet ended. It can be used in similar ways to the bracket or parenthesis by adding a further clarification but it should always be directly relevant to the sentence itself. If it is not directly relevant, use brackets instead. Note that in British English there is a space before and after the dash. Here are some examples of its usage:

"Jane-even though she has a fear of heights-climbed to the top of the hill."

"This is the end of the article-or so you thought."

"Jane Jones, 1956-"

"En" dashes are used to indicate a range of numbers or dates. This can be telephone numbers (a hyphen can also be used here): "555-458-934". In dates and other numbers, the dash is used this way: "April 9-April 13", "pages 89-97". Notice that in these examples there are no spaces left on either side of the dash.

KJ Hutchings is the founder of KJ Language Services, offering editing, writing and proofreading services and advice on how you can make your English language documents the very best they can be. For more information, visit http://www.kjlanguageservices.com/