The term resin originally refers to Latin and Greek names of the “resin of the pine”. Starting from the early years of the plastics industry the name has been applied to wide range of liquid or high viscous components that can harden during use and have sometimes adhesive properties. Currently resins are any natural or synthetic organic compound consisting of a non-crystalline or viscous liquid substance. Natural resins are organic substances that are transparent or translucent, formed in plant secretions. Synthetic resins comprise a large class of synthetic products that have some of the physical properties of natural resins but are different chemically. Most synthetic resins are polymers.