What's the difference between i.e. and e.g.?
mid-14c., from Old French ratifier (13c.), from Medieval Latin ratificare "confirm, approve," literally "fix by reckoning," from Latin ratus "fixed by calculation; determined; approved; certain, sure; valid" (past participle adjective from reri "to reckon, think;" see reason (v.)) + root of facere "to make" (see factitious). Related: Ratified; ratifying.