Alan M. Turing, in full Alan Mathison Turing (born June 23, 1912, London, England—died June 7, 1954, Wilmslow, Cheshire), British mathematician and logician, who made major contributions to mathematics, cryptanalysis, logic, philosophy, and biology and to the new areas later named computer science, cognitive science, artificial intelligence, and artificial life.
Before computers existed, he invented a type of theoretical machine now called a Turing Machine, which formalized what it means to compute a number. Turing’s importance extends far beyond Turing Machines. His work deciphering secret codes drastically shortened World War II and pioneered early computer technology. He was also an early innovator in the field of artificial intelligence, and came up with a way to test if computers could think – now known as the Turing Test.
Besides this abstract work, he was down to earth; he designed and built real machines, even making his own relays and wiring up circuits. This combination of pure math and computing machines was the foundation of computer science.
As a human being, Turing was also extraordinary and original. He was eccentric, witty, charming and loyal. He was a marathon runner with world class time. He was also openly gay in a time and place where this was not accepted. While in many ways the world was not ready for Alan Turing, and lost him too soon, his legacy lives on in modern computing.