This lecture covers the theory and applications of NMR relaxometry, focusing on the principles of spin dynamics, T₂ relaxation, and pore size determination. Practical aspects such as free induction decay, CPMG sequences, and interpretation of relaxation curves are discussed. The lecture also explores the use of NMR relaxometry in studying water dynamics in different environments, including desorption isotherms. Overall, the instructor provides insights into the challenges and opportunities of ¹H NMR relaxometry in material science and environmental research.