The Latin abbreviations e.g. and i.e. are commonly used in English, and nearly as commonly mixed up. Below is a clear explanation, which can also be found online at it’s original home: http://www.elearnenglishlanguage.com/difficulties/egie.html.
I should also point out that these days you can write both ‘eg’ and ‘ie’ without any periods. The only exception would be when writing a legal English text, at which point you should maintain the periods. Notice as well that you need to use a comma after both abbreviations.
e.g. stands for exempli gratia, which means “for example.” Use e.g. to introduce one or more possibilities among many.
I like root vegetables, e.g., potatoes.
(Potatoes are just one of many types of root vegetables)
He wastes his money on junk, e.g. cars that don’t run.
(He also buys old TVs and VCRs)
I’ll listen to anything, e.g., country-western, rap, light jazz.
(Country-western, rap, and light jazz are just a few of the many types of music that I’ll listen to)
An easy way to remember what e.g. means is to think of it as standing for “example given.” Alternatively, just say “eg” out loud – it sounds just like the first syllable in example.
i.e. stands for id est which means “that is.” Use i.e. when what you are introducing is equivalent to or an explanation of what comes before it in the sentence.
I like root vegetables; i.e., the ones that grow underground.
He wastes his money on junk; i.e., stuff that he will never get around to fixing.
I’ll listen to anything; i.e., I like any kind of music.
Basically, i.e. means “in other words.” It’s used to reword or provide an alternate explanation.