I always get mixed up with e.g. and i.e. Hopefully not anymore:
The abbreviation e.g. (from the Latin exempli gratia, ‘for sake of an example’) indicates that one or more examples follow of what has been mentioned in general terms: It could be cheaper by public transport, e.g. by train or coach. The abbreviation i.e. (from Latin id est, ‘that is’) indicates that an explanation follows of what has just been mentioned: Gratuities are discretionary, i.e. you don’t have to leave a tip if you don’t want to.
Source: Tiscali Reference