This is tough,,,,
Although it seems strange light is a wave when you look at it as wave or, better, you try to see it or measure it using tools designed to detect waves (see Young's Double Slit experiment).
It behaves as a particle when you look at it as a particle using tools that "see" particles (check the Photoelectric Effect).
I know it is weird but...
I try to show a picture that can explain what I mean using a single slit and a source of light whose intensity can be varied:
Imagine having a screen as the one of a digital camera where you can record single pixels. Let us start using a very faint source of light; we'll have image (a). Let us then increase the intensity of the light....a pattern starts to emerge!
Imagine that you see the final image...you'll think "I see a wave and diffraction/interference typical of a wave". But if you look at the previous images you'll see particles!
IT is dependent on the frame of reference.
There are many phenomenon which support wave nature of light and others which support particle nature of light .
Wave nature :-we have refraction ,Diffraction ,Young's double slit experiment .
Particle nature :- Photoelectric Effect , Reflection ,etc..
Its entirely dependent on which context you are talking .