Electrical lighting uses approximately 13.7% of the world's electricity and impacts heavily human's visual performance and also well-being, health and security. Electrical power light sources and lighting systems impact also our planet's resources and our biotope. After decades of stagnation of the performances of legacy lighting technologies, products based on Solid State Lighting (SSL) technology have become the most efficient light sources by far that we can find on the market today. Indeed, the advent of SSLs is considered to be the 3 rd revolution in the domain. Today, SSL products and more especially Light Emitting Diodes (LEDs) are mature and are on the way to dominate a market worth of more than $120 billion. Even if someone can argue that innovation in the domain of LED products is decelerating since a couple of years, large-surface, flexible organic light-emitting components opens up new fundamental and technological challenges and offer unsuspected horizons for the light designers of the following decade. Further, the 4 th revolution in lighting is looming: the advent of intelligent and sustainable lighting systems that could transform the way we conceive of the generation of artificial light, by associating it with information and communication technologies, the Internet of Things, technologies that are transforming our society and are taking a prominent place in everyday life. This review paper, is focusing on the lightemitting (LED) and organic light-emitting diode (OLED) technologies. It explains the basic operating principles, highlights the state-of-art and indicates the main challenges for the next decade. Other papers, in this IAS magazine special issue are devoted to extinguishing legacy technologies and rising sustainable smart lighting systems.