A coating is a protective or decorative layer applied to a surface to improve its appearance, performance, or durability. Its fundamental composition includes a binder (resin/polymer) that forms the film, pigments for color and opacity, solvents or carriers to apply it, and additives for enhanced properties like flow, UV resistance, or preservation. 
Introduction to Coatings
Coatings serve various purposes, from protecting against corrosion and abrasion to providing aesthetic appeal and specific functional properties like electrical conductivity. They are applied as a liquid or powder and transform into a solid, protective film on a substrate (the material being coated). 
Protective: Shielding against environmental factors like corrosion, UV radiation, chemicals, and wear.
Decorative: Enhancing appearance with desired color, gloss, texture, and patterns.
Functional: Imparting special qualities such as electrical conductivity, thermal insulation, anti-fouling, or anti-microbial properties. 
Basic Coating Composition
A typical coating formulation is a blend of several key ingredients: 
Binder (Resin/Film-Former): The backbone of the coating that forms a solid film and adheres it to the substrate.
Examples: Natural and synthetic polymers like latex, polyethylene, waxes, and various resins.
Pigments: Provide color, opacity, and can also contribute to corrosion inhibition.
Examples: Titanium dioxide (for whiteness) and extenders or fillers (used to reduce cost and improve performance).
Solvent (Carrier/Dispersant): Dissolves or disperses the binder and pigments, controls viscosity for application, and then evaporates to form the solid film.
Examples: Water (for water-based coatings), organic solvents, or no solvent (for powder coatings).
Additives: Small-quantity components that improve specific coating properties.
Examples: Defoamers, wetting agents (surfactants), flow modifiers, hardeners, preservatives, and UV stabilizers.
Extenders/Fillers: Inexpensive materials used to add bulk, reduce cost, and enhance certain mechanical properties of the coating.