Capacitors are divided into solid capacitors, liquid capacitors, and gas capacitors based on the properties of the dielectric. Among them, solid capacitors are further divided into ceramic capacitors, plastic capacitors, ferroelectric capacitors, etc. Each type of capacitor has its own advantages and disadvantages, and its usage range also varies. Liquid capacitors use liquids (such as sulfuric acid) as dielectrics and are typically composed of electrolytic capacitors, oscillating capacitors, etc. Gas capacitors use gases (such as helium, nitrogen, etc.) as dielectrics and are commonly used in RF circuits to meet the requirements of high-frequency operation. They are composed of transformer type capacitors, spiral capacitors, etc.