What is capacitor and how it is used?

A capacitor is nothing but it is only an electronic devices which store energy from a battery in the form of electric charges.
The terminals of the battery connected to two metal plates which is separated by a non-conducting substance called dielectric. When activated, a capacitor quickly releases electricity in a tiny fraction of a second. 
And most common use of capacitors is energy storage. But Additional uses include power conditioning, signal coupling or decoupling, electronic noise filtering, and remote sensing. Because of its varied applications, capacitors are used in a wide range of industries and have become a vital part of everyday life.