Moonlight is the light that reaches Earth from the Moon

Moon

The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

. This light does not originate from the Moon, but from sunlight

Sunlight

Sunlight, in the broad sense, is the total frequency spectrum of electromagnetic radiation given off by the Sun. On Earth, sunlight is filtered through the Earth's atmosphere, and solar radiation is obvious as daylight when the Sun is above the horizon.When the direct solar radiation is not blocked...

. The Moon does not, however, reflect sunlight like a mirror

Mirror

A mirror is an object that reflects light or sound in a way that preserves much of its original quality prior to its contact with the mirror. Some mirrors also filter out some wavelengths, while preserving other wavelengths in the reflection...

, but it reflects light from those portions of its surface which the Sun

Sun

The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...

's light strikes. See diffuse reflection

Diffuse reflection

Diffuse reflection is the reflection of light from a surface such that an incident ray is reflected at many angles rather than at just one angle as in the case of specular reflection...

.

In folklore, moonlight sometimes has a harmful influence. For example, sleeping in the light of a full moon on certain nights was said to transform a person into a werewolf

Werewolf

A werewolf, also known as a lycanthrope , is a mythological or folkloric human with the ability to shapeshift into a wolf or an anthropomorphic wolf-like creature, either purposely or after being placed under a curse...

.