An electrical substation is used for stepping AC voltage up or down for transmission or distribution. The high voltage is stepped up or down using transformers.
A lightning strike is a natural high-voltage discharge which occurs as a result of the difference in voltage between the negatively-charged base of a cloud and the positively-charged ground.
The spark-gap Tesla coil was invented by Nikola Tesla in 1891. It is a type of resonant transformer capable of generating very high AC voltages. There are many variations of the Tesla coil circuit, such as the solid-state Tesla coil, the dual-resonant solid-state Tesla coil, and the vacuum tube Tesla coil.
The ZVS driver was invented by Vladimiro Mazzilli. It is a type of resonant circuit commonly used for driving flyback transformers, creating high-voltage electrical discharges. It is popular among electronics hobbyists as it is relatively simple and has a low-voltage input.