Documentary films constitute a broad category of nonfictional motion pictures intended to document some aspect of reality, primarily for the purposes of instruction or maintaining a historical record. A 'documentary film' was originally shot on film stock — the only medium available — but now includes video and digital productions that can be either direct-to-video, made as a television program or released for screening in cinemas. "Documentary" has been described as a "filmmaking practice, a cinematic tradition, and mode of audience reception" that is continually evolving and is without clear boundaries.

In popular myth, the word 'documentary' was coined by Scottish documentarian John Grierson in his review of Robert Flaherty's film Moana (1926), published in the New York Sun on 8 February 1926, written by "The Moviegoer" (a pen name for Grierson).

Grierson's principles of documentary were that cinema's potential for observing life could be exploited in a new art form; that the "original" actor and "original" scene are better guides than their fiction counterparts to interpreting the modern world; and that materials "thus taken from the raw" can be more real than the acted article. In this regard, Grierson's definition of documentary as "creative treatment of actuality" has gained some acceptance, with this position at variance with Soviet film-maker Dziga Vertov's provocation to present "life as it is" (that is, life filmed surreptitiously) and "life caught unawares" (life provoked or surprised by the camera).

Nikola Tesla (Serbian Cyrillic: Никола Тесла; 10 July 1856 – 7 January 1943) was a Serbian-American inventor, physicist, mechanical engineer, electrical engineer, and futurist. He was an important contributor to the use of commercial electricity, and is best known for developing the modern alternating current (AC) electrical supply system. His many revolutionary developments in the field of electromagnetism in the late 19th and early 20th centuries were based on the theories of electromagnetic technology discovered by Michael Faraday. Tesla's patents and theoretical work also formed the basis of wireless communication and the radio.

Born in the village of Smiljan (now part of Gospić, present day Croatia), Tesla was a subject of the Austrian Empire by birth and later became an American citizen. Because of his 1894 demonstration of short range wireless communication through radio and as the eventual victor in the "War of Currents", he was widely respected as one of the greatest electrical engineers who worked in America. He pioneered modern electrical engineering and many of his discoveries were of groundbreaking importance. In the United States during this time, Tesla's fame rivaled that of any other inventor or scientist in history or popular culture. Tesla demonstrated wireless energy transfer to power electronic devices in 1891, and aspired to intercontinental wireless transmission of industrial power in his unfinished Wardenclyffe Tower project.

Abraham Lincoln ⁱ/ˈeɪbrəhæm ˈlɪŋkən/ (February 12, 1809 – April 15, 1865) was the 16th President of the United States, serving from March 1861 until his assassination in April 1865. He successfully led his country through its greatest constitutional, military and moral crisis – the American Civil War – preserving the Union while ending slavery, and promoting economic and financial modernization. Reared in a poor family on the western frontier, Lincoln was mostly self-educated. He became a country lawyer, a Whig Party leader, Illinois state legislator in the 1830s, and a one-term member of the United States House of Representatives in the 1840s. After a series of debates in 1858 that gave national visibility to his opposition to the expansion of slavery, Lincoln lost a Senate race to his arch-rival Stephen A. Douglas. Lincoln, a moderate from a swing state, secured the Republican Party nomination. With almost no support in the South he swept the North and was elected president in 1860. His election was the signal for seven southern slave states to declare their secession from the Union and form the Confederate States of America. The departure of the Southerners gave Lincoln's party firm control of Congress, but no formula for compromise or reconciliation was found. And the war came.