A capacitor is a passive device used primarily for electrical energy storage and release. It can serve in many functions, including coupling/decoupling, transient voltage and current suppression, frequency tuning, filtering, DC Block and RF Bypass.
A capacitor is a two-terminal device consisting of 2 metal plates separated by a layer of dielectric. Capacitors can be either fixed or variable and either polarized or non-polarized.
In order to meet a myriad of different requirements, there is an extensive variety of capacitor types available, each one having its own value proposition. Types vary from precision RF tuning/trimming capacitors up to the large power metal can types used in high voltage power inverters, power correction and smoothing circuits.