These eight expressions are often used when something is being renamed or reiterated:
i.e., that is, e.g., for example, to wit, namely, for instance, in other words
The punctuation depends upon where they are in the sentence and/or what follows them. There are six rules; so we will do a few at a time.
WHEN THESE WORDS AND WHAT FOLLOWS ARE AT THE END OF THE SENTENCE:
If followed by a fragment, use a pair of commas.
…I bought a new car, that is, a VW Beetle.
…This is a very serious crime, to wit, murder.
If followed by a complete sentence, use a semicolon and a comma.
…She has to have surgery; i.e., she has to have a hysterectomy.
…He was late that day; in other words, he didn’t make it on time.
If followed by a list, use a colon and a comma.
…Send everything to me: for example, bills, receipts, canceled checks.
…I visited several Oregon towns: namely, Eugene, Portland, Salem, Bend.