The ninth-century Persian scholar at Baghdad's House of Wisdom whose treatise on al-jabr gave algebra its name and its method, whose name became the word 'algorithm,' and who helped carry the Hindu-Arabic decimal system into the Islamic world and eventually into Europe — making him one of the most consequential mathematicians in history, despite almost nothing being known about his life.
Two words in everyday English come from one man: 'algebra' and 'algorithm.' Every time a search engine ranks a result, every time a GPS plots a route, every time a bank calculates interest, something descended from his work is running. He lived in ninth-century Baghdad. He worked at a library the caliph built to collect all human knowledge. His name was Muhammad ibn Musa al-Khwarizmi, and almost nothing about his life is known for certain. What he left behind changed the way the world calculates.