Explore the theoretical foundations of active matter in this lecture from the School on Active Matter at ICTP-SAIFR. Delve into lessons drawn from ideal microscopic models as presented by Aparna Baskaran from Brandeis University, USA. Gain insights into this cutting-edge field of physics over the course of 1 hour and 33 minutes. Part of a comprehensive program held from September 30 to October 4, 2024, this class serves as an excellent introduction to the principles governing active matter systems.