Capacitors are electrical components that can store charge. They consist of two conducting plates separated by a dielectric. When connected to a power source, positive and negative charge build up on opposite plates by removal and addition of electrons. The insulating material stops charge (electrons) moving between the plates, creating a potential difference and a uniform electric field between them.

Capacitance is the amount of charge per unit voltage stored by the capacitor. 

C =frac{Q}{V}

1 Farad is 1 CV-1.  1. Combined capacitance decreases in series: 1 = 1 + 1 + . ..

                                                                                                  1         2

  1. Combined capacitance increases in parallel: = 1 + 2+. ..