Using i.e.
Most people will go their whole lives and never have the need to use i.e.; this is because the simple English words will do the trick. Textbooks, contracts, and other formal documents may employ this Latin abbreviation to save space. Even if you never choose to use i.e. in your own writing, it is likely that you will run across this abbreviation while reading or conducting research.
The punctuation for i.e. can be tricky. Different language usage guides, different countries, and different kinds of writing have variations in the way they punctuate i.e. in sentences. The following guidelines seem to be used consistently, though.
There is no need to use italics (i.e.) when writing this Latin abbreviation. (Other Latin abbreviations are commonly italicized.)
A period follows each of the letters in this abbreviation.
Except at the beginning of a sentence, each letter is in lower case.
A comma usually comes before and after i.e. unless the phrase is in parentheses. In this case, a comma comes after i.e. only. Here is an example of both cases:
Jack and Joseph share an apartment (i.e., rental property that they bought for an investment).
Jack and Joseph share an apartment, i.e., rental property that they bought for an investment.