Energy is typically stored within electrostatic fields (capacitors), magnetic fields (inductor), as mechanical energy (using large flywheels connected to special purpose high current alternators), or as chemical energy (high-current lead-acid batteries, or explosives).
By releasing the stored energy over a very short interval (a process that is called energy compression), a huge amount of peak power can be delivered to a load. For example, if one joule of energy is stored within a capacitor and then evenly released to a load over one second, the average power delivered to the load would only be 1 watt. However, if all of the stored energy were released within one microsecond, the average power would be one megawatt, a million times greater.
Examples where pulsed power technology is commonly used include radar, particle accelerators, ultrastrong magnetic fields, fusion research, electromagnetic pulses, and high power pulsed lasers.