1) Classification according to the change of capacitance: It can be divided into two types: fixed capacitors and variable capacitors.

2) According to the media classification: can be divided into air dielectric capacitors, oil-immersed capacitors and solid medium (mica, paper, ceramic and film) capacitors.

3) Classification by polarity: can be divided into polar capacitors and non-polar capacitors.

Small-capacity capacitors are commonly used in high-frequency circuits such as radios, transmitters, and oscillators. Large capacitors are often used to filter and store charge. Generally, capacitors above 1uF are electrolytic capacitors, while capacitors below 1uF are ceramic capacitors, monolithic capacitors, polyester capacitors, and mica capacitors. Usually, the electrolytic capacitor has an aluminum shell filled with electrolyte and leads two electrodes as positive (+) and negative (-) poles. Unlike other capacitors, their polarity in the PCB manufacturing circuit cannot be wrong. Other capacitors have no polarity.