A Capacitor is a passive electronic component that stores energy in the form of an electrostatic field.

Therefore Capacitors are used to store electric charge. Basically, a capacitor consists of two plates of a conducting material separated by a space filled by an insulator. The insulating layer is called the Dielectric of the capacitor.

Capacitance is directly proportional to the surface areas of the plates, and is inversely proportional to the plates separation.

The capacitor also functions as a filter, passing alternating current (AC), and blocking direct current (DC).

This symbol used to indicate a capacitor is -||-.

The fundamental property of a capacitor is that it can store charge and hence electric field energy. The capacitance C between two appropriate surfaces is defined by V=q\c where V is the potential difference between the surfaces and Q is the magnitude of the charge distributed on either surface

Capacitance is measured in units called
Farad: F
microfarad: µF (1 µF = 10-6 F)
nanofarad: nF (1 nF = 10-9 F)
picofarad: pF (1 pF = 10-12 F)

• Time constant of capacitance
  The time required for a capacitor to get charged is proportional to the capacitance value and the resistance value.
  
  The time constant of a resistance - capacitance circuit is:
  T = R X C
  Where T = time in seconds
  Where R = resistance in ohms
  Where C = capacitance in farads
  
  
• Capacitors in series and parallel
  When Capacitors are connected in parallel say C1,C2,C3,…….
  Add capacitor values together as C1 + C2 + C3 + ..... to get net capacitor value
  
  When capacitors are connected in series.
  The net value is calculated in following manner
  1 / (1 / C1 + 1 / C2 + 1 / C3 + .....)