A Baghdad scholar wrote the book on algebra and lent his Latin name to every algorithm on earth.
Al-Khwarizmi (c. 780–c. 850) was a Persian scholar at Baghdad's House of Wisdom whose book on al-jabr founded algebra as a discipline, and whose Latinized name, Algoritmi, gave us the word 'algorithm' — the step-by-step procedure behind every computer program. He also spread the Indian numerals the world calls Arabic numerals.
Working under the Abbasid caliph al-Ma'mun in the early 9th century, Al-Khwarizmi wrote on mathematics, astronomy and geography at a moment when Baghdad was the richest center of learning on earth. His algebra text of about 830 was translated into Latin in the 12th century and taught in European universities for centuries.
Al-Khwarizmi was born around 780 in Khwarazm, the oasis region south of the Aral Sea in present-day Uzbekistan and Turkmenistan. He made his way to Baghdad, capital of the Abbasid caliphate, where the caliph al-Ma'mun (reigned 813–833) had founded the Bayt al-Hikma — the House of Wisdom — a library, translation bureau and research institute without equal in its age.
There, scholars translated Greek, Persian and Indian works into Arabic and pushed beyond them. Al-Khwarizmi worked as both astronomer and head of the library, moving between the mathematics of India, the astronomy of Persia and the geometry of Greece, and fusing them into something new.
Around 830 he wrote 'Kitab al-Mukhtasar fi Hisab al-Jabr wal-Muqabala' — The Compendious Book on Calculation by Completion and Balancing. It was the first systematic treatment of solving linear and quadratic equations: rules, worked examples, proofs by geometry. 'Al-jabr', the restoration of a broken part, became 'algebra'.
The book was practical, not abstract: it solved problems of inheritance under Islamic law, trade, land measurement and the digging of canals. Translated into Latin in 1145 by Robert of Chester, it carried algebra into Europe, where the word and the method stuck.
His treatise on arithmetic explained the Hindu decimal positional system — the digits 0 to 9 and the place-value notation that makes modern calculation possible. Its Latin translation circulated under the title 'Algoritmi de numero Indorum' — Al-Khwarizmi on the Indian numbers — and readers took the author's name for the method itself. Hence 'algorithm'.
He also compiled astronomical tables, the Zij al-Sindhind, used to predict the positions of the sun, moon and planets, and wrote 'Kitab Surat al-Ard' (The Image of the Earth), a geography listing the coordinates of cities and landmarks across the known world.
Every smartphone runs on two of his gifts: the numerals in which we count and the algorithms by which machines decide. Algebra and the decimal system underpin modern mathematics, science and computing alike — a 9th-century Baghdadi scholar's working notes, still running the world.
A crater on the Moon is named Al-Khwarizmi in his honor, and his books survived in Latin manuscripts that European scholars copied for four hundred years.
