Word History: Because of its popularity over the last century, one might figure algorithm for a new coinage. The source of algorithm, however, is not Silicon Valley but Khwarizm, a region near the Aral Sea in south-central Asia and the birthplace of the ninth-century mathematician Muhammad ibn-Musa al-Khwarizmi (780?-850?). Al-Khwarizmi, "the Khwarizmian," who later lived in Baghdad, wrote a treatise on what is called algorism, or the use of Arabic numerals for mathematical computation. Despite the name by which the Arabic numerals are known in Europe, these symbols, as well as the methods for using them, were actually developed in ancient India. Europeans learned to use the numerals, however, through treatises written in Arabic by mathematicians working in the Muslim world. Algorism, the English word for computation with Arabic numerals, is derived from Al-Khwarizmi's name. The word algorithm originated as a variant spelling of algorism, probably under the influence of the word arithmetic or its Greek source arithmos, "number." With the development of sophisticated mechanical computing devices in the 20th century, algorithm was adopted as a convenient word for a recursive mathematical procedure, the computer's stock-in-trade. In its new life as a computer term, algorithm, no longer a variant of algorism, nevertheless reminds us of the debt that modern technology owes to the scientists and scholars of ancient and medieval times.