Jean-Paul Delahaye is s a professor at the University of Lille and a research fellow in the Laboratory of Fundamental Information Technology (LIFL). He is the author of numerous mathematical works for the general reader.
Nicolas Gauvrit teaches mathematics at the University of Artois, France. He has a special interest in the links between mathematics and psychology.

The development of electronic databases (and of Internet search engines to explore them) has given rise to such new behaviours as egosurfing: estimating your own popularity or fame by entering your name in a search engine like Google to see how many pages come up. You can also search the Internet to evaluate a friend’s or a celebrity’s reputation. The results may seem surprising: in October 2012 Lady Gaga was more ‘famous’ than Jesus Christ. Attempts to ‘grade’ scientists and universities using other databases have met with resistance, in the form of various biases that are analysed here and which must be taken into account to avoid misconceptions.
The Net has put vast libraries at our fingertips. Thanks to Harvard University’s multilingual digital collections, it is now possible to consult five million books and to analyse the changing usage of a word or expression over the past two centuries. This new approach can serve to clarify age-old questions in a variety of fields, from history or psychology to mathematics.

• From the history of shop-worn expressions to the evolution of artistic taste over the ages, from the notion of ‘positive bias’ to Benford’s Law, this concise, entertaining guide will enable readers to discover the subtleties of ‘culturetech’, a digital approach to culture.