LIGHT:

light or electromagnetic radiation may be viewed in one of two complementary ways: as a wave in an abstract electromagnetic field, or as a stream of massless particles called photons.

What do you expect? Is light a particle or a wave?

 see this video to know the answer.

Thus, Light define as a Wave.

CHARACTERISTICS:

 1.Wavelength.

2. Frequency (how many wavelengths pass a fixed point in a given time).

3. Energy.

the relationship between the three characteristics are in the following equation:

You can also reed more about 

The reflection and refraction of light

http://physics.bu.edu/~duffy/py106/Reflection.html