The book includes 9 chapters on the current status of world cotton production, genetic diversity and genetic gain through breeding in cotton, introgression breeding to broaden the genetic diversity of cotton, development of genetic populations and molecular markers, molecular linkage mapping of major genes and quantitative trait loci (QTLs) and association mapping, molecular cloning of candidate genes for important traits, and molecular and genomics assisted breeding in cotton. This part also deliberates fundamentals and applications of genetic engineering including genome editing and genetically engineered commercial cotton, and mutagenesis for genomics studies. The work further includes six chapters that presents deliberations on genomes for almost all the cotton species (Gossypium spp.) with an emphasis on A, D, and AD genome species, comparative genomics among various cotton species, and functional genomes in general and specifically transcriptomics and metabolomics.