This document discusses the history and concepts of molecular modelling in drug design. It describes how early drug design involved trial and error methods to find biologically active molecules through random screening. The development of X-ray crystallography in the 1970s allowed visualization of 3D molecular structures, advancing drug design. Molecular modelling uses computer techniques based on chemistry and experimental data to analyze molecules and predict properties. The first generation of rational drug design used quantitative structure-activity relationships based on 2D structures. The second generation involves molecular modelling to simulate molecular interactions and design molecules meeting biological requirements through direct and indirect approaches as well as database searches and 3D computer-aided drug design.