Detection, identification and classification of yeasts have undergone a major transformation in the past decade and a half following application of gene sequence analyses and genome comparisons. Development of a database (barcode) of easily determined gene sequences from domains 1 and 2 (D1/D2) of large subunit rRNA and from the internal transcribed spacer (ITS) now permits many laboratories to identify species accurately and this has led to a doubling in the number of known species of yeasts over the past decade. Phylogenetic analysis of gene sequences has resulted in major revision of yeast systematics, resulting in redefinition of nearly all genera. Future work calls for application of genomics to refine our understanding of the species concept and to provide a better understanding of the boundaries of genera and higher levels of classification. This increased understanding of phylogeny is expected to allow prediction of the genetic potential of various clades and species for biotechnological applications and adaptation to environmental changes.