One of my readers asked me the following grammar question as a follow-up to this post:

I would appreciate a lesson on the use of the hyphen in sentence construction. I use it sparingly when I think I am using it correctly, but I am never quite sure frankly...My question is … can the hyphens be used as a substitution for commas or is their usage different?

Well, firstly, as listed in every editor's bible, the Chicago Manual of Style, there are three types of dashes - hyphens, en dashes, and em dashes. They all have different functions, and to make life fun, are all different lengths (the dash used in this sentence is an em dash):

1. The hyphen is the shortest of the three dashes, and is used in the following ways:
   1. hyphens can connect two words, such as "hair-raiser," "eye-opener."
   2. hyphens are used in compound numbers, "thirty-seven," "forty-nine."
   3. hyphens are used with the prefixes, ex-, self-, and all, e.g. ex-boyfriend, self-assured, and all-encompassing.

   The hyphen can be found on the keyboard on the underscore key, next to the "0" computer key.

2. Now we come to the en dash, which is longer in length than the hyphen, and is used to connect continuing, or inclusive, numbers, e.g. the years 1968-72, 10:00-5:00 P.M.

   The en dash can be found on the keyboard by pressing Ctrl and the grey minus key on the numeric keyboard.

3. Last but not least, the em dash, which is double the size of the en dash, and is used in the following ways:
   1. The em dash, or a pair of dashes, can be used to denote a sudden break in thought:

      I know a person—let's call her Elizabeth—who is extremely gregarious.

   2. And now, in answer to your question, Alan, an em dash can also be used to separate ideas in a sentence which is long and complex, or in one that has an excessive amount of commas:

      On our way to see my brother and sister-in-law in Modi'in—which is located between Jerusalem and Tel Aviv—we stopped off at a cafe for a bite to eat.