In this 31-minute lecture from the ICTP-SAIFR Minicourse on Partial Differential Equations: Analytical and Numerical Tools, Professor Oscar Reula from the National University of Córdoba, Argentina explores the heat equation with a focus on energy estimates. Learn fundamental analytical techniques for understanding the behavior and properties of the heat equation through rigorous mathematical analysis. This class forms part of a comprehensive educational program running from May 5 to June 30, 2025, designed to build expertise in both theoretical and practical aspects of partial differential equations.