Computational methods are nowadays essential tools employed in the field of drug design. Indeed, bringing a molecular compound from bench to clinic is a challenging, time-consuming and expensive goal to achieve. Computer-aided drug design (CADD) techniques aim to simplify this process, by in-silico identifying compounds active against a critical macromolecular target. With the knowledge of the molecular structure of the compounds and preferably also of the target of interest, virtual screening can produce a high-confidence, limited set of small molecules to be tested experimentally, reducing enormously both the time and the cost otherwise required for the in-vitro screening. Computer simulations of ligand-receptor complexes provide also structural insights of the interactions which can rationally drive the hit-to-lead optimization process.