Iniferters are initiators that induce radical polymerization that proceeds via initiation, propagation, primary radical termination, and transfer to initiator. Because bimolecular termination and other transfer reactions are negligible, these polymerizations are performed by the insertion of the monomer molecules into the iniferter bond, leading to polymers with two iniferter fragments at the chain ends. The use of well‐designed iniferters would give polymers or oligomers bearing controlled end groups. If the end groups of the polymers obtained by a suitable iniferter serve further as a polymeric iniferter, these polymerizations proceed by a living radical polymerization mechanism in a homogeneous system. In these cases, the iniferters (CS bond) are considered a dormant species of the initiating and propagating radicals. In this article, I describe the history, ideas, and some characteristics of iniferters and living radical polymerization with some iniferters that contain dithiocarbamate groups as photoiniferters and several compounds as thermal iniferters. From the viewpoint of controlled polymer synthesis, iniferters can be classified into several types: thermal or photoiniferters; monomeric, polymeric, or gel iniferters; monofunctional, difunctional, trifunctional, or polyfunctional iniferters; monomer or macromonomer iniferters; and so forth. These lead to the synthesis of various monofunctional, telechelic, block, graft, star, and crosslinked polymers. The relations between this work and other recent studies are discussed. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2121–2136, 2000