Cathy O'Neil is a world class number shark. After a fancy education, she ended up at hedge fund doing, in the words of Lloyd Blankfein, "God's work." Much like Blankfein, she came to regret it. She witnessed how insurance companies, banks, and advertisers used massive hauls of internet harvested personal information, aka “Big Data,” to make decisions regardless of the human consequences. While at the hedge fund, these were known as “financial instruments.” O’Neil started to call them WMDs = Weapons of Math Destruction.

She quit the hedge fund and decided to write a book about WMDs. “Weapons' ” role in the financial crisis of 2008 are well documented, but I’ve buried the lede. The reason I’m recommending this book now is that O’Neil explains, in easy to understand language, how Facebook uses data to generate ad revenue. More generally, how data mining advertisers use aggregated details to push information at target groups, or sell the ability to do so regardless of the consequences.

Besides her short book decoding socio-economic discord, O’Neil writes about all things numbers at her blog Mathbabe.