The École normale supérieure (ENS) in Paris will host a special event focused on data and artificial intelligence (AI) on September 25, 2026, from 5 p.m. to midnight. Known as the "Nuit de l'ENS," the event will include over 70 conferences, debates, workshops, exhibitions, and performances across the ENS campus on rue d'Ulm. Admission is free, but attendees must register in advance. The event will explore AI from a wide range of angles, including its role in scientific discovery, medicine, natural disaster management, psychology, and education. An opening round table will bring together experts such as Philippe Aghion, Joëlle Barral, Anne Bouverot, Stéphane Mallat, Joëlle Pineau, Marc Mézard, and ENS director Frédéric Worms. Discussions will also examine how data shape our understanding of the world, covering topics like public health history, climate data, political conflicts, globalization, and the rise of China or the economic changes in Europe. The evening will also consider the impact of data on democratic life, including their use by governments, in elections, and in cybersecurity. A session titled "Big Data, Big Brother. How States Govern by Data" will explore how data are used in the exercise of power, while another session will ask whether it is possible to balance the use of data with the protection of personal privacy. Data will also be viewed as an economic asset. Economist Philippe Askenazy will discuss how methods for calculating wealth in digital economies are evolving to incorporate data more effectively. Literature, arts, and history will also be featured, with an exhibition revisiting W.E.B. Du Bois's "data portraits," which used graphs, colors, and statistics to challenge racist stereotypes of African Americans. Another exhibition, "Save endangered writings: data, AI and cultural memory of the Southwest," will highlight efforts to preserve endangered writing systems in Southwest China using linguistics, anthropology, digitization, and AI. In addition to academic and artistic programs, the event will offer family-friendly activities. Starting at 5 p.m., a session for young children will be led by Olivier Cappé, who will introduce AI in an accessible way, continuing from his book "Understanding (or almost) Artificial Intelligence" (CNRS Éditions, 2025). Other family-oriented events will include "Save the teddy bears with artificial intelligence," exploring medicine design, telescope data, and the MathAData workshop at the intersection of mathematics and AI.