i.e. vs. e.g.

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Q: What's the difference between "i.e." and "e.g."? I thought they were interchangeable, but I was told that this isn't the case. Can you please explain?—Claire Collord

A: I used to have the most difficult time remembering this rule. After all, both of these terms are derived from Latin and I didn't take Latin in school—I opted for the Spanish class that was taught by an exceptionally attractive maestra (which may have explained the C-). But with a little help from a college friend, I was able to burn the i.e./e.g. grammatical law into my brain once and for all.
The rough translation is as follows:

i.e. means "that is." (id est)
e.g. means "for example." (exempli gratia)

The difference here is that i.e. is exclusive while e.g. is a sample. They are not interchangeable because they change the meaning of the sentence. And if you substitute in the definitions, it'll help you determine which letter-combination you need.

Let's take these examples:

I like summer sports (e.g., baseball, softball, ultimate Frisbee). The sports mentioned (baseball, softball, ultimate Frisbee) represent a few of the summer sports that I like, but aren't the only ones I enjoy (I also like fishing, sand volleyball and golf). I'm just offering some examples. If you read this sentence as "I like summer sports (for example, baseball, softball, ultimate Frisbee)" you see what I mean. So the correct choice is e.g.

On the other hand, Sophie likes winter sports, i.e., skiing and hockey. This sentence indicates that Sophie likes the specific winter sports skiing and hockey, but not necessarily any other winter sports. You can read this sentence: Sophie likes winter sports, that is, skiing and hockey. So the choice here is i.e.

To burn these definitions into your memory and help remind you which letter-abbreviation pairs with which definition, you can follow this mnemonic device a college friend once taught me: i.e. is "in essence" while e.g. is "eggs sample."

"Eggs sample" may make me laugh each time I think about it, but I never forget the rule.

Brian A. Klems is the online managing editor of Writer’s Digest magazine.

Have a question for me? Feel free to post it in the comments section below or e-mail me at WritersDig@fwpubs.com with “Q&Q” in the subject line. Come back each Tuesday as I try to give you more insight into the writing life.