A review of the available ceramic dielectrics shows that they fall into two groups: non-ferro-electric materials, which have low losses and high stability, and ferro-electric materials, which have very high permittivities and higher losses and are not so stable. The latter behave in a manner analogous to ferromagnetic materials; their properties, besides being highly field-dependent, also vary considerably with temperature.The most suitable shapes for capacitors are derived from a consideration of the process of manufacture of ceramic materials. Capacitors in electronic circuits are classified according to their functions. Ceramic capacitors fulfil admirably the requirements for low- or controlled-temperature-coefficient capacitors in tuned circuits as by-pass capacitors at higher frequencies, because of their small size and low self-inductance. Ceramic capacitors can be used in equipment of all power levels, from hearing-aids to high-power transmitters.