The book is mainly designed for the undergraduates and the graduates studying basic and applied medical and veterinary parasitology, epidemiology, and public health in and outside Nepal. It may be considered as a landmark in carrying out the research on parasites and understanding the parasitic infection in the hosts. The book projects definitions, properties of parasites, and wide approaches of parasitology in the context of epidemiology, ecology, and association. Moreover, it presents some reported parasites and their infections in Nepal. The most important issues the author raises here are about the problems of high prevalence and high density of parasites in Nepalese people living in rural and city areas. The book finally gives the new vista of prevention of the parasites and parasitic infections directed by a leader, who can be true parasitologist.