algorithm (n.)
An algorithm is a set of steps for solving a problem or carrying out a calculation.
The word ultimately comes from the name of the ninth-century mathematician al-Khwarizmi. A Latin version of a work associated with him on Hindu-Arabic numerals used a form of his name, Algoritmi. That name gave rise to algorism, a word for arithmetic using those numerals.12
Over time, the spelling and meaning changed. Algorithm came to mean a defined procedure for calculation and then, more broadly, a step-by-step procedure for solving a problem.12
The search engine uses an algorithm to rank results.