Traditional methodologies for drug discovery can be classified according to the availability of target and ligand structures (Figure ). The conventional drug categorisation discovery methodologies encompass four primary groups ( ): (i) Library design, (ii) Structure-based design, (iii) Ligand-based design, (iv) De Novo Design (Figure ). In addition to traditional classification, it is possible to introduce a novel category known as the quantum mechanical simulations and chemoinformatics approach, which can be considered novel classes. The overview shows that target and ligand structures define the categorisation of conventional approaches for drug discovery. Structural-based drug discovery (SBDD) is a technique for developing small molecules using the three-dimensional conformation of the target protein. By contrast, ligand-based drug discovery (LBDD) mostly focuses on structural and chemical analysis of known ligands. While de novo design is carried out to produce new chemical entities, library design involves screening chemical libraries. Every tactic has special advantages and is quite important for the medication development process.