Nikola Tesla (Serbian Cyrillic: Никола Тесла) (10 July 1856 – 7 January 1943) was a Serbian American inventor, physicist, mechanical engineer, and electrical engineer. Born in Smiljan, Croatian Krajina, Military Frontier he was an ethnic Serb subject of the Austrian Empire and later became an American citizen. Tesla is best known for his many revolutionary contributions to the discipline of electricity and magnetism in the late 19th and early 20th century. Tesla's patents and theoretical work formed the basis of modern alternating current electric power (AC) systems, including the polyphase power distribution systems and the AC motor, with which he helped usher in the Second Industrial Revolution. Contemporary biographers of Tesla have deemed him "The Father Of Physics" and "the man who invented the twentieth century" and "the patron saint of modern electricity."
After his demonstration of wireless communication (radio) in 1893 and after being the victor in the "War of Currents", he was widely respected as America's greatest electrical engineer. Much of his early work pioneered modern electrical engineering and many of his discoveries were of groundbreaking importance. During this period, in the United States, Tesla's fame rivaled that of any other inventor or scientist in history or popular culture, but due to his eccentric personality and unbelievable and sometimes bizarre claims about possible scientific and technological developments, Tesla was ultimately ostracized and regarded as a "mad scientist". Never having put much focus on his finances, Tesla died impoverished at the age of 86.
The SI unit measuring magnetic flux density or magnetic induction (commonly known as the magnetic field ), the tesla, was named in his honour (at the Conférence Générale des Poids et Mesures, Paris, 1960).
Aside from his work on electromagnetism and engineering, Tesla is said to have contributed in varying degrees to the establishment of robotics, remote control, radar and computer science, and to the expansion of ballistics, nuclear physics, and theoretical physics. In 1943, the Supreme Court of the United States credited him as being the inventor of the radio. Many of his achievements have been used, with some controversy, to support various pseudosciences, UFO theories, and early new age occultism. Tesla is honoured in Serbia and Croatia, as well as in Czech Republic (he was awarded the highest order of the White Lion by Czechoslovakia) and in unofficial ways in his adopted home, the United States.