Solid state, at its most basic level, means "no moving parts." Therefore, solid state electronic devices are made up of solid components that do not move. Some examples include computer motherboards and integrated circuits. Devices that use only solid state parts, such as television sets, speakers, and digital watches, are often referred to as solid state products.
Flash memory devices are solid state products, while hard drives are not. This is because hard drives use a spinning disk and moving drive head to read and write data, while flash memory uses electric charges to perform the same functions. For this reason, flash memory devices are seen as more durable than hard drives. This is why flash memory is often used in products such as portable MP3 players and digital cameras.
Because solid state devices have no moving parts, they are less likely to break down than devices that have mobile mechanisms. For this reason, it is often more worthwhile to buy an extended warranty on electronics that have moving parts than those that do not. That is something you may want to think about next time you are shopping.