What’s up with the hyphen, the en dash, and the em dash?

A hyphen (-) is used to join words (e.g., “mother-in-law”) or to separate the syllables of the same word, e.g., at the end of a line if the word doesn’t fit:

Never put a space before or after a hyphen.

NOTE: When it comes to en dashes and em dashes, different style guides (e.g., Associated Press, The Chicago Manual of Style, Guardian) have different rules and preferences, so if you are required to adhere to a certain style, you should consult the appropriate guide.

Style preferences aside, an en dash (–) is slightly wider than a hyphen, and it usually replaces “to” between a range of numbers:

• Although it is generally viewed that a space before and after an en dash is optional, you should ask your teacher what he or she prefers.
• An en dash got its name because it is the width of an n.
• To make an en dash on a Mac, push option and - at the same time. 

An em dash (—) is the widest of the three. It can be used in place of a colon, commas, and parentheses:

We can also use an em dash to express the source of a quotation:

Lastly, em dashes can show that a speaker has been interrupted. (This usage will come in handy if you’re writing dialogue or fiction.)

• Similar to the first bullet point regarding en dashes, you should ask your teacher if he or she wants a space before and after an em dash; different teachers will give different answers.
• An em dash got its name because it is the width of an m.
• To make an em dash on a Mac, push option + shift + - at the same time.

The above explanations give you a big picture look at hyphens, en dashes, and em dashes. When it comes to the fine details (e.g., putting spaces before and after a dash), consult your teacher or his or her preferred style guide.

(Pete Wentz GIF source: GIPHY; T.O.P GIF source: exitclov.tumblr.com)