Scintillators are materials that are able to emit photons when impinged with ionizing radiations. This family of materials is covered by both organic and inorganic structures, with some similarities but also with different photophysical processes occurring underneath. The scientific fields and communities are in fact rather separated, while it would benefit from more interactions and collaborations. This book is mostly focused on plastic scintillators, which are polymer-based materials, and the purpose of this chapter is to introduce and link them to well-known inorganic scintillators. In addition, hybrids materials are new developments based on inorganic nanocrystals in organic host. In such hybrid materials, a complex interplay occurs along the energy relaxation leading to the emission of light. Thanks to their chemical versatility, plastic scintillators can easily be modified. Whereas the first decades have seen their use as “all-purpose” detectors, the most recent developments afford specialization of the materials toward a given application. Thus, various modification stages are possible: the simplest is to tune its chemical properties. In addition, this material is an optical device, and complicated photophysical phenomena occur in the radiation/matter interaction volume. Finally yet importantly, current developments in artificial intelligence, as well as highly sophisticated algorithms, are used to overcome intrinsic limitations of plastics properties. This chapter thus gives a historical perspective on the development of plastic scintillators with a mention of past and current main actors. Then, a discussion follows on the basic principles in plastic scintillation design. Their main properties are finally presented and compared with inorganic scintillators. Some of these properties will be partially discussed herein since they will be fully explained in dedicated chapters.