The laws of inheritance were considered quite superficial until 1903, when the chromosome theory of heredity was established by Sutton and Boveri. The discovery of the double helix and the genetic code led to our understanding of gene structure and function. For the past quarter of a century, remarkable progress has been made in the characterization of the human genome in order to search for coherent views of genes. The unit of inheritance termed factor or gene, once upon a time thought to be a trivial an imaginary entity, is now perceived clearly as the precise unit of inheritance that has continually deluged us with amazement by its complex identity and behaviour, sometimes bypassing the university of Mendel"s law. The aim of the fifth volume, entitled Genes and Genomes, is to cover the topics ranging from the structure of DNA itself to the structure of the complete genome, along with everything in between, encompassing 12 chapters. These chapters relate much of the information accumulated on the role of DNA in the organization of genes and genomes per se. Several distinguished scientists, all pre-eminent authorities in each field to share their expertise. Obviously, since the historical report on the double helix configuration in 1953, voluminous reports on the meteoric advances in genetics have been accumulated, and to cover every account in a single volume format would be a Herculean task. Therefore, only a few topics are chosen, which are of great interest to molecular geneticists. This volume is intended for advanced graduate students who would wish to keep abreast with the most recent trends in genome biology.