* Polyvinyl chloride (PVC) itself.

PVC is a polymer, meaning it's a large molecule made up of repeating units of a smaller molecule called vinyl chloride. This molecule has the chemical formula CH2=CHCl, which is why PVC is sometimes called "poly(chloroethylene)".

While PVC is the primary component, it's often blended with other additives to improve its properties for different applications. These additives include:

* Plasticizers: To make the PVC more flexible and pliable.

* Stabilizers: To prevent the PVC from degrading in sunlight or heat.

* Fillers: To add strength, reduce cost, or change the color of the PVC.

* Lubricants: To aid in processing and reduce friction.

* Pigments: To color the PVC.

So, while PVC is the main ingredient, it's the combination with these additives that creates the diverse range of PVC products we encounter in everyday life.