Before there was LOL and TLDR and STFU, we had other abbreviations that helped us to quickly and easily convey ideas. These still have a useful place in our writing, because they still help us quickly and easily convey ideas. They are i.e. and e.g., and they are not the same thing.
I.e. stands for “id est” in Latin, which means “that is” or “in other words.” When you use i.e., you are explaining what you mean in another way. You’re clarifying.
Need a mnemonic device to help you remember? Imagine that i.e. stands for “in essence.”
I am a perfectionist when it comes to my work — i.e., this project might take me a while.
I only packed a carry-on for my holiday (i.e., I only brought a couple of outfits).
She is vegan; i.e., she won’t eat any animal-based products.
A comma should come after “i.e.,” followed by the clarifying statement. What comes before it (a comma, a semicolon, an em dash) depends on what the abbreviation is introducing or how much you want to emphasise it. You can also set it off in parentheses. The same goes for e.g.
E.g. stands for “exempli gratia” in Latin, which means “for example.” E.g. signifies that you’re giving one or more possibilities, but it’s not a comprehensive list.
Need a mnemonic device to help you remember? You could imagine that the “E” in e.g. stands for “Example.”
My kids watch a lot of cartoons that I find annoying — e.g., Caillou.
My town hosts several festivals each fall, e.g., an apple festival and Oktoberfest.
Make sure you pack up everything you need for the pool (e.g., sunscreen and a towel).
What about etc.?
You’re probably already using this one correctly, but it’s worth a quick note that etc. — short for “et cetera” — isn’t a replacement for i.e. or e.g. Instead, etc. means “and the rest.” It’s usually (but not always) at the end of the sentence and it indicates you’re including all the other items in a category.
If you can substitute etc. with “and so on,” you’re using it correctly.
Example: The buffet offered sandwiches, soup, salad, rolls, etc.
(Don’t ever put “and” before etc. — that would be redundant, like saying “and and the rest.”)
When all else fails and you’re still not sure whether to go with i.e. or e.g., stick with “in other words” and “for example.” Those are perfectly fine, too.