A capacitor is a component, that discharges and charges, while circuits are on (charged) or off (discharged).
Capacitors in a BankEdit
Sometimes, capacitors can be on a bank, by in Microfarads (uF), but they may take a while to charge them in a bank while the power is on.
Capacitor plague was a phenomena witch caused higher than expected premature failure rate of aluminum electrolytic capacitors with non-solid or liquid electrolyte of certain brands, especially from some Taiwanese manufacturers. The capacitors fail because of a special water based corrosion effect, due to a poorly formulated electrolyte. When this happens the capacitor expands and bursts.
Many consumer electronics have been affected by capacitor plague most notably, computers, some of which are still being used today.