Maybe it’s because I’m an English professor (read: geek), but I find the nuances of punctuation fascinating. For me, punctuation isn’t (just) about a series of rules that must be slavishly followed. Most of the time, punctuation rules are there to guide our understanding of the surrounding text. Witness, one of my favorite examples:

A woman: without her, man is nothing.

versus

A woman without her man is nothing.

Another example–the infamous Oxford comma (you know, the one before the last item in a series). Some people maintain that the comma isn’t necessary. But without it, you can get some serious ambiguity. Take, for example, this book dedication (from the Wikipedia article on serial commas):

To my parents, Ayn Rand and God.

It should read:

To my parents, Ayn Rand, and God.

Unless, of course, you’re delusional and think that you’re some sort of semi-divine offshoot. Then I think the first could work.
 

 Today’s tip is a useful little schematic that helps me explain to my students the differences between parentheses, commas, and dashes.

*A parenthesis indicates to the reader that the parenthetical information is less important than the surrounding text.

Ex. I tried to avoid meeting Matt (my ex) at the reception. This example tries to signal to the reader that the person, rather than their former relationship status, is what’s important here.

*Commas put the parenthetical information on equal standing with the surrounding text.

Ex. I tried to avoid meeting Matt, my ex, at the reception. The tone here is a matter-of-fact explanation.

*Dashes are used to highlight information. They draw attention to themselves–and should thus be used sparingly–too many dashes on a page make it hard for the eye to find a focal point (as you may find from my example here). Incidentally, a dash is made by putting two hyphens together. (Microsoft Word will automatically format this into an em-dash for you.) In my freelance editing work I often see writers who confuse the dash with the hyphen–although I’m sure you all are above that!

Ex. I tried to avoid meeting Matt–my ex–at the reception. All of a sudden, that parenthetical information becomes the most important information in the sentence. Without more context, we don’t know why, but we know to pay attention to this information.