I.e. vs. E.g

Today's topic: I.e. or e.g.?

Deciding  whether to use i.e. or e.g. tends to give people fits.  Some writers just decide which abbreviation they think sounds better, and use that one for everything.  There are rules for when to use each one, however, and the two are not interchangeable.  So let's get this sorted out once and for all.

What i.e. and e.g. stand for:
I.e. stands for the Latin phrase "id est," which essentially means "that is."  E.g. stands for the Latin phrase "exempli gratia," which means "for instance" or "for example."  This alone should go some way toward helping you distinguish between them, but let's go a little further.

When to use which:
There are a few tricks that experts advise using to help you remember when to use which abbreviation.  For example, internet "Grammar Girl" Mignon Fogerty says to remember that i.e., which starts with i, means "in other words," and that e.g., which starts with e, means "for example."  E: for example.  I: in other words.  I find this trick to be the most helpful.

If you don't like that tip, try remembering it this way: "e.g." looks a bit like the word "egg," which rhymes with "example."  E.g. = for example.  "I.e." could stand for "in essence," which is quite similar to its actual meaning, "in other words."

Examples:

E.g.: "for example."  Use e.g. to tell readers that you are about to give them an example of something.

"I love desserts, e.g. cheesecake and gelato." 

Note that I love plenty of other desserts other than cheesecake and gelato; my use of "e.g." doesn't indicate that I'm going to give you a comprehensive list of ALL the desserts I like.  It just indicates that I'm giving you a couple of examples to illustrate my point.

"He likes watching sports, e.g. baseball and basketball."

Similarly, the use of "e.g." in this sentence implies that the guy likes watching lots of different sports, not just baseball and basketball.  Those are just given as two examples from a list that probably includes quite a few others as well.

I.e.: "in other words."  Use i.e. to introduce a detailed, specific clarification.  If I only loved two desserts--cheesecake and gelato--then I'd want to use i.e., as in:

"I love desserts, i.e. cheesecake and gelato."

In this example, because I used "i.e.," you can deduce that cheesecake and gelato are the only two desserts I love.

"He likes watching sports, i.e. baseball and basketball."

In this example, the use of "i.e." tells us that this guy only likes watching two sports, baseball and basketball.

Still confused?
There's no reason why you absolutely HAVE to use the abbreviations, so if you're still a little fuzzy on which is which, just spell out what you mean, either "for example" or "in other words."

To read Mignon Fogerty's excellent post on the particulars of e.g. and i.e. (including how to punctuate them), click here: http://www.quickanddirtytips.com/education/grammar/ie-versus-eg

I hope this has helped clarify when to use these two often-troublesome abbreviations.  Happy scribbling!