This presentation introduces capacitors and their mechanism. It explains that a basic capacitor contains two parallel plates separated by an insulating material, and that it stores electrical charge between the plates. The unit of capacitance is the Farad. Common types of capacitors include mica, ceramic, plastic film, and electrolytic capacitors, which are polarized. Variable capacitors can adjust capacitance and are used in devices like radios. Modern technology uses semiconductor variable capacitors called varactors.