The term solid state is widely used in the computer industry to indicate the new generation of hard drives no longer equipped with a magnetic disk and head, but rather a flash memory, this technology is also called SSD (Solid State Drive).
In the nautical sector, the term is widely used for nautical stereos and mainly means that the stereo does not have a CD/DVD player where it is necessary to have a mechanical device for reading the information contained in the support.
This evolution is important for the nautical sector, where the mechanical elements are the most sensitive to the agents of the marine environment, thus extending the life of the device. This has been made possible by the evolution of digital flash memory media that are replacing the use of CD. So often in place of the CD player we find today SD card slots, USB ports and Apple Dock 30-pin input, of course in addition to the old but still functional AUX input.