The abbreviations i.e. and e.g. can often be confused. I.e. originates from the Latin id estmeaning ‘that is to say’ and is used to add explanatory information or to state something in different words, as in:

A walking boot which is synthetic, i.e. not leather.

E.g. also originates from Latin: exempli gratia, meaning ‘for example’. Whereas i.e. is used to introduce a clarification, e.g. is used to introduce examples, as in:

Life events (e.g. birth, death, and marriage).

As e.g. and i.e. have been created specifically for use in writing, they should be written in lower-case roman (not italics), with two full stops and no spaces.