Paint is a liquid, liquefiable, or mastic composition that, after application to a substrate in a thin layer, is converted to a solid film. It is most commonly used to protect, color, or provide texture to objects. Paints are used to decorate, protect, and prolong the life of natural and synthetic materials, and act as a barrier against environmental conditions. Paints may be broadly classified into decorative paints, applied on-site to decorate and protect buildings and other objects, and industrial coatings, which are applied in factories to finish manufactured goods such as cars.

The constituents of paint include:

• Pigment(s): prime pigments to impart color and opacity
• Binder (resin): a polymer, often referred to as resin, forming a matrix to hold the pigment in place
• Extender: larger pigment particles added to improve adhesion, strengthen the film, and save binder
• Solvent (sometimes called a thinner): either an organic solvent or water is used to reduce the viscosity of the paint for better application. Water-borne paints are replacing some paints that use volatile organic compounds such as the hydrocarbons which are harmful to the atmosphere
• Additives: used to modify the properties of the liquid paint or dry film

The pigment for paint is both man-made and natural, and it is made by crushing minerals into a fine powder-like texture. It is meant to be mixed with water, oil, or another base. Most paints use either oil or water as a base (the diluent, solvent, or vehicle for the pigment) . Paints are formulated according to their proposed use - primer, undercoat, special finishes (matt, gloss, heat resistance, anti-corrosion, abrasion resistance) .

The chemistry of paint involves the use of various chemicals, compounds, and components such as barium sulfate, resins, fillers, toluene/xylene, and isocyanates. Binders, which are the resin portion of the paint, are usually a blend of resins that fall into a couple of broad classes, such as alkyd, acrylic, or epoxy. The paints that do polymerize are often sold as two-part kits that are mixed together before application. Otherwise, they are thermally cured or designed to react with moisture in the air.

In summary, paint is a liquid, liquefiable, or mastic composition that is converted to a solid film after application to a substrate in a thin layer. It is used to protect, color, or provide texture to objects. Paints are formulated according to their proposed use and contain various chemicals, compounds, and components such as pigments, binders, extenders, solvents, and additives.