The variable message displays with LED technology are electronic tools for the visual communication, controlled by a CPU. These devices are able to memorize and visualize dozens of informative and advertising messages, in several formats and different timing. In the last few years the world of LED visualization faced an impressive revolution. This technology made available even for small and medium businesses an fundamental advertising tool, able to visualize high impact promotional messages. Luminous displays with LED (acronym of Light Emitting Diode) technology, are composed by a LED matrix controlled by a CPU. These electronic signs are low consumption and very long lasting and can have a incredibly high resolution. LED technology improved drastically in the past decades. Particularly in the past 5 years new production techniques have been developed to increase LEDs' brightness and reduce the decay. All these innovations allow LED bright signs to keep functioning for over 10 years without changing the LEDs.