A branch of genetics that studies heredity and variation chiefly in farm animals but also in domestic and wild animals. It is based on general genetic principles and concepts, and it mainly uses the hybrid, cytological, population, ontogenetic, mathematical-statistical, and twin methods of general genetics. The population method is useful in studying the distribution of individual genes in animal populations. In very simple cases when there is segregation of one or more genes, the frequencies of occurrence of individual genes serve as parameters characterizing populations. This book is a complete introductory note containing divergent topics of Genetics under one cover. The subject has been presented in the sequence in which the discoveries in the Science of Genetics were made commencing with the Mendelian Genetics covering Cytogenetics, Molecular Genetics and Population Genetics and culminating with the Applied Genetics.