 A short but up-to-date review on the role of dyes in the photoinitiation process as a polymerization reaction is presented. Radical and catalytic reactions are largely encountered in the radiation curing and the imaging areas for use in traditional coating applications as well as in high-tech sectors such as nanofabrication, computer-to-plate processing, laser-direct imaging, manufacture of optical elements, etc. And promising developments concerned with the introduction of the siloradical chemistry that enhances the polymerization efficiency are also discussed. This article was authored by Christian Leigh, Jacques Lalavie, Xavier Alonas, and others.