Book excerpt: Since 1996, when the first Saccharomyces cerevisiae genome sequence was released, a wealth of genomic data has been made available for numerous S. cerevisiae strains, its close relatives, and non-conventional yeast species isolates of diverse origins. Several annotated genomes of interspecific hybrids, both within the Saccharomyces clade and outside, are now also available. This genomic information, together with functional genomics and genome engineering tools, is providing a holistic assessment of the complex cellular responses to environmental challenges, elucidating the processes underlying evolution, speciation, hybridization, domestication, and uncovering crucial aspects of yeasts´ physiological genomics to guide their biotechnological exploitation. S. cerevisiae has been used for millennia in the production of food and beverages and research over the last century and a half has generated a great deal of knowledge of this species. Despite all this, S. cerevisiae is not the best for all uses and many non-conventional yeast species have highly desirable traits that S. cerevisiae does not have. These include tolerance to different stresses (e.g. acetic acid tolerance in Zygosaccharomyces bailii, osmotolerance in Z. rouxii, and thermotolerance in Kluyveromyces marxianus and Ogataea (Hansenula) polymorpha), the capacity of assimilation of diverse carbon sources (e.g. high native capacity to metabolyze xylose and potential for the valorization of agroforest residues by Scheffersomyces (Pichia) stipites), as well as, high protein secretion, fermentation efficiency and production of desirable flavors, capacity to favor respiration over fermentation, high lipid biosynthesis and accumulation, and efficient production of chemicals other than ethanol amongst many. Several non-Saccharomyces species have already been developed as eukaryotic hosts and cell factories. Others are highly relevant as food spoilers or for desirable flavor producers. Therefore, non-conventional yeasts are now attracting increasing attention with their diversity and complexity being tackled by basic research for biotechnological applications. The interest in the exploitation of non-conventional yeasts is very high and a number of tools, such as cloning vectors, promoters, terminators, and efficient genome editing tools, have been developed to facilitate their genetic engineering. Functional and Comparative Genomics of non-conventional yeasts is elucidating the evolution of genome functions and metabolic and ecological diversity, relating their physiology to genomic features and opening the door to the application of metabolic engineering and synthetic biology to yeasts of biotechnological potential. We are entering the era of the non-conventional yeasts, increasing the exploitation of yeast biodiversity and metabolic capabilities in science and industry. In this collection the industrial properties of S. cerevisiae, in particular uses, are explored along with its closely related species and interspecific hybrids. This is followed by comparisons between S. cerevisiae and non-conventional yeasts in specific applications and then the properties of various non-conventional yeasts and their hybrids.