While I was working today I learned that people often miss use i.e. and e.g. in their writing. I was actually looking for the correct way to write i.e. (caps vs. no caps, periods vs. no punctuation, etc.), however I ended up learning so much more!
I.e. stands for the Latin words "id est". In English that would translate to "that is" or "in other words", an easy way to remember it's meaning would be to think of it as saying "in effect" or "in essence". You would use this abbreviation if you were modeling what something should be like or what it is; i.e., when you want to clarify something. E.g., She wore a sapphire scarf; i.e., her scarf was blue.
E.g. on the other hand, stands for the Latin words "exempli gratia", or in English "For example". An easy way to remember this abbreviation would be to remember e.g. means "example(s) given". You would use e.g. when you wanted to give one or more examples of something; e.g., My kids like to play board games; e.g., Battleship, Risk, and Chess.
*I.e and e.g. do not need to be put in italics, but they should be separated by periods.
*In the U.S. they should be followed by commas, but in Europe they would consider that double punctuation and the comma should be left off. I know several people that follow them with a colon, but can find no references of that being correct (or incorrect for that matter).
*Most people believe that putting i.e. or e.g. inside of parentheses is redundant, but there are a few who say it is okay. If the abbreviation follows a complete sentence it is better to use a semicolon after the sentence then add the abbreviation and added comment, ending with a period. If the abbreviation is given mid-sentence, you would just separate it by commas.
*Many people believe that you should not use "etc." when using i.e. or e.g. as they both indicate incomplete lists. However, I do not believe this is a solid rule (more of an opinion really); i.e., if you were saying to someone, "Many animals swim in water, to name a few, fish, sharks, turtles, and so on and so forth." you could shorten that to, "Many animals swim in water; i.e., fish, sharks, turtles, etc."
*I.e. and e.g. should be in all lowercase letters, unless they start a new sentence.
This is just the information that I learned today, if anyone has any added information on this topic, I would love some more input!