Refraction, reflection, transparent, translucent and opaque!
Refraction is a change of direction of a light Ray when it passes across two substances that have different densities eg. Glass and air!
When a ray of light hits a surface and bounces back into your eye.
When light can pass through an object eg. Glass
When an object will some light through it, but not all light. Eg. Tissue paper
When light is completely unable to pass through an object.