Writing tip: i.e. isn't the same as e.g.
What a difference a letter can make! You might think that i.e. and e.g. can be used interchangably, but they don't mean the same thing. Whereas i.e. is the abbreviation of the Latin term id est, which basically means "that is", e.g. stands for exempli gratia, which means "for example" (Fogarty, 2011, p. 1).
To decide which abbreviation to use, first decide whether you are reiterating a message or giving an example. Reiterating a message gives further clarification on a topic, whereas giving an example illustrates a point. To remember which abbreviation to use in what setting, consider the Grammar Girl's advice:
E.g. means “for example,” so you use it to introduce an example: I like card games, e.g., bridge and crazy eights. Because I used e.g., you know that I have provided a list of examples of card games that I like. It's not a finite list of all card games I like; it's just a few examples.
On the other hand, i.e. means “in other words,” so you use it to introduce a further clarification: I like to play cards, i.e., bridge and crazy eights. Because I used i.e., which introduces a clarification, you know that these are the only card games that I enjoy. (Fogarty, 2011, p. 2)
With both i.e. and e.g., there should be periods after each letter, there shouldn't be a space between the first period and the second letter, the abbreviations should not be italicized, and a comma should follow the final period of the abbreviation. Finally, when using e.g., it's usually not necessary to include "etc." at the end of the list of examples. Using e.g. involves providing a few examples, not a comprehensive list, so it's implied that there are other examples.
Please contact the Writing Centre if you have any questions.
Writing centre coordinator
Fogarty, M. (2011, May 19). I.e. versus e.g. [Blog posting]. Retrieved from http://www.quickanddirtytips.com/education/grammar/ie-versus-eg