Use i.e. when you mean "that is" or "in other words": it says exactly what you mean. Use e.g. when you mean "for example": it gives one or more examples from a longer list.
There is no shame in admitting that you cannot tell i.e. from e.g., or that you only ever use one of them because you are not sure how to use them correctly. Many people have the same problem, and some even think the two mean the same thing. After reading this article, you will be able to use both correctly and never mix them up again.
To know how and when to use these two abbreviations, you first have to learn what they stand for. Then you can look at how they work in a sentence. There are examples for each part.
What they mean
- i.e. is short for the Latin id est, which means "that is".
- e.g. is short for the Latin exempli gratia, which means "for the sake of example", or simply "for example".
That alone tells you that the two abbreviations are not the same.
How to use them
In both abbreviations, each letter is followed by a period. In American English, both are usually followed by a comma; in British English, the comma is often left out. Many style guides discourage i.e. and e.g. in formal writing and prefer the full words: "that is" and "for example" or "for instance". If you do use the abbreviations in formal writing, many style guides recommend keeping them inside parentheses.
i.e.
You use i.e. to make sure the reader knows exactly what you are talking about. It identifies, specifies, clarifies, or expands on what you have just said.
For example:
Patting an angry dog is like trying to jump off a cliff, i.e., a very dangerous thing to do.
e.g.
You use e.g., on the other hand, to give an example of what you have just said. It adds no further information; it only lists some of the possible items or choices. The list is open: it names some possibilities, but not all of them.
For example:
There are so many things we could do on the weekend, e.g., go to the mall or watch a movie.
One sentence, two meanings
In some sentences, choosing i.e. or e.g. changes the meaning:
- Some of my friends (i.e., Marcus and Lisa) don't want to go to the party tonight.
- Some of my friends (e.g., Marcus and Lisa) don't want to go to the party tonight.
In the first sentence, with i.e., Marcus and Lisa are the only friends who do not want to go to the party. The list is complete.
In the second sentence, with e.g., Marcus and Lisa are among the friends who do not want to go, but they may not be the only ones. The list is open, and other friends may want to stay away as well.
How to remember the difference
Mixing up i.e. and e.g. can cause misunderstandings or completely change what you say about the things or people you name. So it pays to use them correctly.
Remembering the difference is easy. Think of it like this:
- i.e. = identify (or "in essence")
- e.g. = example (or "example given")
Now you should not mix them up anymore. For more on shortened forms, see all you need to know about acronyms. Before you publish, check your text for spelling, grammar, and punctuation mistakes.