Moonlight is the light that is perceived as coming from the moon.  Moonlight is in fact sunlight reflected from the Moon.  The intensity of moonlight varies greatly depending on the current lunar phase; but even the full moon provides only a faint illuminaion of about 0.2 lx (so full moon is about 500,000 times fainter than the sun).  One cannot read books or discern colors under moonlight.

To "moonlight" is to work at a second job—to work in the moonlight rather than day light.

See also: Moonlight Sonata, Moonshine