When I was at school, I was taught chemistry by one of those particularly pedantic teachers. He instilled upon us not only that an acid plus a base gives a salt plus water, but also the correct usage of the abbreviations e.g. and i.e.
A lot of websites I have seen recently seem to use the two abbreviations interchangeably. However, they mean different things, and proper usage uses only the correct one. Incorrect usage appears unprofessional to those that know the difference and can propagate misuse by others, especially if that website is considered influential.
Part of the problem could be that people don’t understand what the abbreviations represent: each stands for a Latin phrase:
- e.g. = exempli gratia ‘for the sake of example, for example’
- i.e. = id est ‘that is’.
For example, e.g.
To give an example of something, use e.g. as in (1).
- She likes to read horror stories, e.g. Pet Sematary, The Fog and The Exorcist.
If we used i.e. in (1), it would mean that she only likes to read those particular horror stories, and the sentence reads a bit awkwardly. However, these are only a sample of the horror stories she likes to read.
Note that it’s best to give more than one example of something so that the reader can infer other examples. She likes a Stephen King book and one by James Herbert, so we can infer that she also likes The Shining and The Rats.
That is, i.e.
To clarify or give further information about something, use i.e. (example 2).
- He likes to read in his spare time, i.e. reading is his hobby.
If we used e.g. in (2), it would read badly. We’d have to rephrase it, which could end up altering the meaning: He has several hobbies, e.g. reading. Can you think of a better way to rephrase the sentence in (2)?
Notice that a comma precedes e.g. and i.e. (3) but does not follow either (4).
- Polar bears live only one place, i.e. the North Pole.
- Polar bears live only one place, i.e., the North Pole.
How to remember which is which
If you didn’t study Latin at school, it might be hard to remember these: you might need a mnemonic! Think about whether you’re giving an example or additional information:
- example → eggzample → e.g.
- that is → that id→ id est→ i.e.
This probably won’t work for everyone. If you can can come up with a better mnemonic than that, leave it in the comments – you might help someone else!
Some style guides may state that you write e.g. and i.e. out in full (5) anyway, unless they’re used in brackets (6), in which case there is no preceding comma.
- The rained stayed away, that is it was dry all day.
- The fancy goods shop sold items (e.g. candles, clocks and ornaments) suitable for gifts.
Which of the following sentences give examples (e.g.) and which clarify or give more information (i.e.)? (Answers below.)
- The shop sold baked goods, ___ bread, cakes and pastries.
- The shop was a bakery, ___ it sold products like bread, cakes and pastries.
- Walls can be built from different materials (___ stone, bricks, concrete) and can be tall or short.
- The doctor said it wouldn’t last long, ___ three to four days.
- They bought a Californian chardonnay, ___ a wine from the New World.
- [On an Internet form]
Enter your company name, ___ MyBusiness:
How did you get on?
If you didn’t do so well, perhaps you should write out the words in full – the English, not the Latin! – for absolute clarity until you get the hang of the abbreviations.
Use e.g. to give several examples of the preceding text.
Use i.e. to clarify or supplement the preceding text.
Now that you’re an expert on e.g. and i.e. – go forth and exemplify and clarify to your heart’s content!