Gossypium, as the one of the biggest genera, the most diversity, and the highest economic value in field crops, is assuming an increasingly important role in studies on plant taxonomy, polyploidization, phylogeny, cytogenetics, and genomics. Here we update and provide a brief summary of the emerging picture of species relationships and diversification, and a set of the designations for individual genomes and chromosomes in Gossypium. This cytogenetic and genomic nomenclature will facilitate comparative studies worldwide, which range from basic taxonomic exploration to breeding and germplasm introgression.