Reflection:

When the ray incident on a conducting surface it reflects making an same angle with normal is called reflection.

OR

Reflection is the change in the direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated.

Refraction:

Refraction is the bending of the wave when it enters a medium where the speed is different. The refraction of light when it passes from a fast medium to a slow medium bends the light ray towards the normal to the boundary between the two media.

Due to change in speed of light when it travels from different medium as air,water,glass nad other transparent material .

Absorbtion in scattering:

Absorption is the process where impurities in the fibre absorb optical energy and dissipate it as a small amount of heat, it scatters light in all direction when it hits a point.