Before the availability of computer technology, many drugs were discovered by accident or trial and error. At the current epoch, a new system has emerged—rational drug design, a way of developing drugs with the help of computers. Computers are being used to aid in designing and testing new drugs. Genetic tests can be used to determine an individual’s response to a specific medication. Computer-aided drug was being used to help combat human immunodeficiency virus (HIV)/AIDS, tuberculosis, malaria, hepatitis C. Powerful computers allow scientists to create graphical models. Developing drugs by design requires mapping the structure and creating a three-dimensional graphical model of the target molecule. This process involves a lot of mathematical calculations, and without computers the process took donkey years; after the calculations were completed, a wire model of the molecule had to be constructed. Now, supercomputers accurately do the calculations in a small fraction of the time, and graphical software produces the image on a computer screen.