Vinyl siding is plastic exterior siding for houses and small apartment buildings, used for decoration and weatherproofing, imitating wood clapboard, batten board and batten or shakes, and used instead of other materials such as aluminum or fiber cement siding. It is an engineered product, manufactured primarily from polyvinyl chloride (PVC) resin. In the UK and New Zealand a similar material is known as uPVC weatherboarding.

Siding or wall cladding is the protective material attached to the exterior side of a wall of a house or other building. Along with the roof, it forms the first line of defense against the elements, most importantly sun, rain/snow, heat and cold, thus creating a stable, more comfortable environment on the interior side. The siding material and style also can enhance or detract from the building's beauty. There is a wide and expanding variety of materials to side with, both natural and artificial, each with its own benefits and drawbacks. Masonry walls as such do not require siding, but any wall can be sided. Walls that are internally framed, whether with wood, or steel I-beams, however, must always be sided.