Turing is best known for his work at Bletchley Park, where UK cryptologists sought to decipher messages sent by the Nazis. His efforts to crack Germany's Enigma code remained a secret for decades but are now credited with saving thousands of lives and hastening the end of World War II. Turing was played by Benedict Cumberbatch in "The Imitation Game," a 2014 film on the subject.
The pioneering scientist also played a pivotal role in developing computers, and early thinking about artificial intelligence.
In 1937, he published a paper introducing an idea that came to be known as the Turing machine, which is considered to have formed the basis of modern computing. This was a hypothetical device that could come up with a solution to any problem that is computable.
Two years after choosing castration to avoid a custodial sentence, he ended his life at the age of 41 by eating an apple laced with cyanide.
Sex between men over the age of 21 was decriminalized in England and Wales in 1967. However the law was not changed in Scotland until 1980 and in Northern Ireland until 1982.
British Prime Minister Gordon Brown apologized for Turing's treatment by the justice system in the 1950s after thousands of people signed a petition in 2009.
He received a royal pardon in 2014. Turing was chosen to grace the £50 note from a list of candidates including theoretical physicist Stephen Hawking and mathematician Ada Lovelace.