“I feel it in my fingers, I feel it in my toes, the love that is all around me.” These might be the words of a popular Christmas song from the movie Love Actually, but this could just as easily be a song about macromolecules—large molecules all around us. From your nails and hair to the rubber tips on your earphones, they are everywhere. You are made of macromolecules and so are trees and plastic water bottles! We call them polymers—long stretches of identical molecules with a range of useful properties, like toughness or stretchiness. And, it turns out, we just cannot live without them. Polymers occur both naturally—the DNA in our cells is a polymer—and synthetically (man-made), like plastic, Silly Putty and Styrofoam. This article uncovers the mysteries of polymers and explains how these fascinating materials have shaped life as we know it.