i.e. vs e.g.
i.e. (you will rarely if ever see this capitalized) is Latin for id est, or that is, as in that is to say… Or – you know what’s coming – in other words… It gives more information on what you were just talking about. “We’ll go on the first day of the sale, i.e., tomorrow.” If you don’t already know when the sale is, the first part of the sentence does not tell you when you’ll be going. The i.e. clears that up, so you now know you’ll be going tomorrow.
e.g. (see parentheses above) is Latin for exempli gratia, i.e., for example. “I love the smells of summer, e.g., BBQ, sno cones, suntan oil.”
Both of these are always preceded and followed by a comma, e.g., a specific type of punctuation.