Algorithms were around for a very long time before the public paid them any notice. The word itself is derived from the name of a 9th-century Persian mathematician, and the notion is simple enough: an algorithm is just any step-by-step procedure for accomplishing some task, from making the morning coffee to performing cardiac surgery. Computers use algorithms for pretty much everything they do -- adding up a column of figures, resizing a window, saving a file to disk. But all those things usually just happen the way they're supposed to. We don't have to think about what's going on under the hood. But algorithms got harder to ignore when they started taking over tasks that used to require human judgment -- deciding which criminal defendants get bail, winnowing job applications, prioritizing stories in a news feed.