A polymer is a larger molecule that is formed by the combination of many smaller molecules of the same kind.
They are made of long repeating chains of molecules called monomers.
Polymers may be naturally found in plants and animals (natural polymers), naturally occurring polymers and undergo further chemical modification (semi-synthetic polymers), or may be man-made (synthetic polymers).
Some examples of polymers include starch, polyethylene, Nylon-6, Nylon-6,6, Teflon, etc.