Hidden from view, complex to understand and often controversial, algorithms are at the heart of computer coding that underpins modern society. Every time we search the internet, every time we pay by credit card, even the romantic partners suggested to us by online dating sites – they’re all powered by algorithms. And their reach is growing all the time, as some societies use them to automate decisions regarding criminal justice, mortgage applications and job recruitment.

The history of algorithms is surprisingly ancient, stretching back to the Babylonian empire where large societies required a systematic way to count and order different aspects of citizens’ lives. Today some people are questioning their use, as some algorithms have been shown to replicate bias and there are fears that algorithms have the potential to undermine democracy.

Bridget Kendall is joined by Ramesh Srinivasan, Professor in the Department of Information Studies at the University of California Los Angeles and the author of Beyond the Valley: How Innovators around the World are Overcoming Inequality and Creating the Technologies of Tomorrow; the French computational scientist, consultant and entrepreneur Aurélie Jean, who’s published From the Other Side of the Machine: A scientist’s journey in the land of algorithms; and Ian Stewart, Emeritus Professor of Mathematics at Warwick University who’s written more than 120 books on aspects of mathematics and science.

Produced by Fiona Clampin for the BBC World Service

[Image: Digital data and binary code. Credit: Yuichiro Chino/Getty Images]