Linum (flax) is a genus of about 200 species in the flowering plant family Linaceae. The genus includes common flax, which is one of the best fibers to produce linen, the seeds to produce linseed oil and has health-related properties of flax in human and animal nutrition. This book describes the genetics and genomics of Linum including the development of extensive experimental resources (e.g. whole genome sequence, efficient transformation methods, insertional mutant collections, large germplasm collections, resequenced genomes) that have led much progress and its economic importance. The methods and use of Linum to address a wide range of applications (e.g. disease resistance, cell wall composition, abiotic stress tolerance, floral development, natural diversity) is also discussed.