Polyethers-polymers with the structural element (R'-O-R)(n) in their backbone-are an old class of polymers which were already used at the time of the ancient Egyptians. However, still today these materials are highly important with applications in all areas of our life, reaching from the automotive and paper industry to cosmetics and biomedical applications. In this Review, different aliphatic polyethers like poly(epoxide)s, poly(oxetane) s, and poly(tetrahydrofuran) are discussed. Special emphasis is placed on the history, the polymerization techniques (industrially and in academia), the properties, the applications as well as recent developments of these materials.