Solid-state refers to electronic components, devices, and systems based entirely on the semiconductor.

In a solid-state component, the current is confined to solid elements and compounds engineered specifically to switch and amplify it. Current flows in two forms: as negatively charged electrons, and as positively charged electron deficiencies called holes. In some semiconductors, the current consists mostly of electrons; in other semiconductors, it consists mostly of holes. Both the electron and the hole are called charge carriers.

An example of a non-solid-state component is a cathode-ray tube (CRT). In this device, electrons flow freely through a vacuum from an electron gun, through deflecting and focusing fields, and finally to a phosphorescent screen.