Absorption of electromagnetic radiation is how matter takes up a photon's energy (typically electrons within atoms).  This transforms EM energy into internal energy of the absorber (thermal energy).  

Reflected light can be divided into two subtypes, specular reflection and diffuse reflection.  

Specular reflection, also known as regular reflection, is the mirror-like reflection of waves, such as light, from a surface. The result is that an image reflected by the surface is reproduced in mirror-like (specular) fashion. 

Specular reflection reflects all light which arrives from a given direction at the same angle, whereas diffuse reflection reflects that light in a broad range of directions. 

Reflections that undergo scattered reflections are called diffuse reflections. 

Atoms or molecules which are exposed to light absorb light energy and re-emit light in different directions with different intensity. This phenomenon, called scattering, is a general physical process where some forms of EM radiation, such as light, are forced to deviate from a straight trajectory by one or more paths.  

Reflections that undergo scattering are often called diffuse reflections.

Transparency is the physical property of allowing light to pass through the material without appreciable absorption & scattering. Translucency (or translucence) allows light to pass through but can be scattered where there is a change in chemistry of the material. 

Materials which do not transmit light are called opaque. 

Refraction is the change in direction of a light wave passing from one material to another or from a gradual change in the medium. How much a wave is refracted is determined by the change in wave speed and the initial direction of wave propagation relative to the direction of change in speed. 

Diffraction refers to various phenomena that occur when a wave encounters an obstacle or a slit (aperture). It is defined as the bending of waves around the corners of an obstacle or through an aperture.