Have you seen the little forms e.g. and i.e. and wondered what they meant? Okay, I’ll tell you. But first, be aware that you use abbreviated forms like these only in informal or technical documents, or documents where space is at a premium (catalogs, forms, etc.).

You use i.e. when you mean “that is.” The origin of i.e. is “id est.”

You use i.e. when you’re restating the idea (to be more explicit) or expanding upon it.

Example: We provide all retailers with the standard discount, i.e., 10%.

You use e.g. when you mean “for example.” The origin of e.g. is “exempli gratia.”

Example: Shertzer’s book has a number of elements, e.g., punctuation, capitalization, parts of a sentence, and confusing words.

In American English, generally follow i.e. and e.g. with a comma.

Thanks to Bonnie Larner for the use of a photo of her cats, Weezer and Charlie.