What's the difference between i.e. and e.g.?
1560s, from Middle French prélude "notes sung or played to test the voice or instrument" (1530s), from Medieval Latin preludium "prelude, preliminary," from Latin praeludere "to play beforehand for practice, preface," from prae- "before" (see pre-) + ludere "to play" (see ludicrous). Purely musical sense first attested in English 1650s. Related: Prelusion.