Algorithms decide what we are recommended on Amazon, what films we are offered on Netflix. Sometimes, newspapers warn us of their creeping, insidious influence; they are the mysterious sciencey bit of the internet that makes us feel websites are stalking us—the software that looks at the e-mail you receive and tells the Facebook page you look at that, say, Pizza Hut should be the ad it shows you. Some of those newspaper warnings themselves come from algorithms. Crude programs already trawl news pages, summarise the results, and produce their own article, by-lined, in the case of Forbes magazine, "By Narrative Science".
An algorithm, at its most basic, is not a mysterious sciencey bit at all; it is simply a decision-making process. It is a flow chart, a computer program that can stretch to pages of code or is as simple as "If x is greater than y, then choose z".
What has changed is what algorithms are doing. The first algorithm was created in the ninth century by the Arabic scholar Al Khwarizami—from whose name the word is a corruption. Ever since, they have been mechanistic, rational procedures that interact with mechanistic, rational systems. Today, though, they are beginning to interact with humans. The advantage is obvious. Drawing in more data than any human ever could, they spot correlations that no human would. The drawbacks are only slowly becoming apparent.