La Terasse des audiences du Clair de lune---what to do with 3 clefs?

[mamaswami]

This song by Debussy has three lines, or clefs.  Why?  I don't have three hands. Does this mean to just use whatever hand is free?  Tips or insight?

[coda_colossale]

For the ease of reading, of course. There are numerous examples in piano literature for two hands that have been notated in more than two staves. Most of the Debussy Preludes in Book II, parts of Navarra by Albéniz, the chordal section of Prelude in C# minor by Rachmaninoff, parts of the cadenza from Prokofiev's 2nd Piano Concerto, Opus Clavicembalisticum by Sorabji, Liszt's transcription of Ave Maria etc. It is usually quite obvious with which hand you're supposed to play the extra staff. Otherwise look for m.s. and m.d. markings.

[j_menz]

For the ease of reading, of course.

That's the theory. I have never found it true in practice.

@mamaswami - Whilst top (of 2) staff = RH, bottom = LH is often true, it is not universally so. Sometimes the other hand is used as convenience dictates. With three staves (or more) often one or other hand takes two of them and the other hand the remaining one(s) - but again that is not always true. It's basically up to you to work out which distribution works best.  Suggested fingering may be a guide, or as coda_colossale suggests md and ms markings (ms = LH, md = RH).