Why algorithms are called algorithms | BBC Ideas

We think of an algorithm as something new, but the term actually dates back about 900 years. The word algorithm comes from the name of a Persian mathematical genius, Muhammad ibn Musa al-Khwarizmi. He was born around 780 AD in the region now known as Uzbekistan.

His name suggests he came from Khwarizm. Known as al-Khwarizmi, he was director in the House of Wisdom, an intellectual centre for scholars in 9th Century Baghdad. He made innovative contributions to mathematics, astronomy, geography and cartography, and wrote an influential book called Concerning the Hindu Art of Reckoning.

300 years later, the book was rediscovered and translated into Latin. It introduced Hindu-Arabic numerals to the West, which eventually replaced the unwieldy Roman ones. The Hindu-Arabic number system, along with the decimal point, both described by al-Khwarizmi in his book, are the basis of the numbers we use throughout the world today.

Al-Khwarizmi's name, when Latinised in the title of the book, became algoritmi. And this is the origin of the word algorithm. We also have al-Khwarizmi to thank for the word algebra, which comes from another of his works.

His books revolutionised mathematics in the West, showing how complex problems could be broken down into simpler parts and solved. In medieval Latin, algorismus simply meant the decimal number system. By the 13th Century, it had become an English word and was used, for example, by Chaucer.

But it wasn't until the late 19th Century that algorithm came to mean a set of step-by-step rules for solving a problem. In the early part of the 20th Century, Alan Turing, the British mathematician and computer scientist, worked out how, in theory, a machine could follow algorithmic instructions and solve complex mathematics. This was the birth of the computer age.

During World War Two, he built a machine called the Bombe, which used algorithms to crack the Enigma code. Today algorithm is a fairly common term, even if sometimes you're not exactly sure what an algorithm does. Algorithms are everywhere now, helping us to get from A to B, driving internet searches, making recommendations of things for us to buy, watch or share.

And predicting how we vote or who we fall in love with. This little word that originated in medieval Persia is gradually transforming our lives. Thanks for watching!

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