Michael Faraday (UK: /ˈfærəˌdeɪ/ FAR-uh-day, US: /ˈfærədi/ FAR-uh-dee; 22 September 1791 – 25 August 1867) was an English chemist and physicist who contributed to the study of electrochemistry and electromagnetism. His main discoveries include the principles underlying electromagnetic induction, diamagnetism, and electrolysis. Although Faraday received little formal education, as a self-made man, he was one of the most influential scientists in history. It was by his research on the magnetic field around a conductor carrying a direct current that Faraday established the concept of the electromagnetic field in physics. Faraday also established that magnetism could affect rays of light and that there was an underlying relationship between the two phenomena. He similarly discovered the principles of electromagnetic induction, diamagnetism, and the laws of electrolysis. His inventions of electromagnetic rotary devices formed the foundation of electric motor technology, and it was largely due to his efforts that electricity became practical for use in technology. The SI unit of capacitance, the farad, is named after him.

As a chemist, Faraday discovered benzene and carbon tetrachloride, investigated the clathrate hydrate of chlorine, invented an early form of the Bunsen burner and the system of oxidation numbers, and popularised terminology such as "anode", "cathode", "electrode" and "ion". Faraday ultimately became the first and foremost Fullerian Professor of Chemistry at the Royal Institution, a lifetime position.

Faraday was an experimentalist who conveyed his ideas in clear and simple language. His mathematical abilities did not extend as far as trigonometry and were limited to the simplest algebra. Physicist and mathematician James Clerk Maxwell took the work of Faraday and others and summarised it in a set of equations which is accepted as the basis of all modern theories of electromagnetic phenomena. On Faraday's uses of lines of force, Maxwell wrote that they show Faraday "to have been in reality a mathematician of a very high order – one from whom the mathematicians of the future may derive valuable and fertile methods."

A highly principled scientist, Faraday devoted considerable time and energy to public service. He worked on optimising lighthouses and protecting ships from corrosion. With Charles Lyell, he produced a forensic investigation on a colliery explosion at Haswell, County Durham, indicating for the first time that coal dust contributed to the severity of the explosion, and demonstrating how ventilation could have prevented it. Faraday also investigated industrial pollution at Swansea, air pollution at the Royal Mint, and wrote to The Times on the foul condition of the River Thames during the Great Stink. He refused to work on developing chemical weapons for use in the Crimean War, citing ethical reservations. He declined to have his lectures published, preferring people to recreate the experiments for themselves, to better experience the discovery, and told a publisher: "I have always loved science more than money & because my occupation is almost entirely personal I cannot afford to get rich."

Albert Einstein kept a portrait of Faraday on his study wall, alongside those of Isaac Newton and James Clerk Maxwell. Physicist Ernest Rutherford stated, "When we consider the magnitude and extent of his discoveries and their influence on the progress of science and of industry, there is no honour too great to pay to the memory of Faraday, one of the greatest scientific discoverers of all time."

Michael Faraday was born on September 21, 1791 in Newington Butts, Surrey, which is now part of the London Borough of Southwark. His family was not well off. His father, James, was a member of the Glasite sect of Christianity. James Faraday moved his wife, Margaret (née Hastwell), and two children to London during the winter of 1790 from Outhgill in Westmorland, where he had been an apprentice to the village blacksmith. Michael was born in the autumn of the following year, the third of four children. The young Michael Faraday, having only the most basic school education, had to educate himself.

At the age of 14, he became an apprentice to George Riebau, a local bookbinder and bookseller in Blandford Street. During his seven-year apprenticeship Faraday read many books, including Isaac Watts's The Improvement of the Mind, and he enthusiastically implemented the principles and suggestions contained therein. During this period, Faraday held discussions with his peers in the City Philosophical Society, where he attended lectures about various scientific topics. He also developed an interest in science, especially in electricity. Faraday was particularly inspired by the book Conversations on Chemistry by Jane Marcet.

In 1812, at the age of 20 and at the end of his apprenticeship, Faraday attended lectures by the eminent English chemist Humphry Davy of the Royal Institution and the Royal Society, and John Tatum, founder of the City Philosophical Society. Many of the tickets for these lectures were given to Faraday by William Dance, who was one of the founders of the Royal Philharmonic Society. Faraday subsequently sent Davy a 300-page book based on notes that he had taken during these lectures. Davy's reply was immediate, kind, and favourable. In 1813, when Davy damaged his eyesight in an accident with nitrogen trichloride, he decided to employ Faraday as an assistant. Coincidentally one of the Royal Institution's assistants, John Payne, was sacked and Sir Humphry Davy had been asked to find a replacement; thus he appointed Faraday as Chemical Assistant at the Royal Institution on 1 March 1813. Very soon, Davy entrusted Faraday with the preparation of nitrogen trichloride samples, and they both were injured in an explosion of this very sensitive substance.