I always see this mistake made in text books— the incorrect usage of either i.e. or e.g., when explaining things.  You should use i.e. when restating the idea.  You should use e.g. when giving an example.  In Latin, i.e. stands for id est which means “that is.”  E.g. is Latin for exempli gratia, basically “for example.”  I don’t want to misuse these words in any of my writings; e.g., essays, posts, forged doctors’ notes.  It can get confusing when combining other abbreviations and acronyms; e.g., i.e., E.T., B.E.T, etc., etc. This is confusing; i.e., none of this seems to make sense.