Sorghum is a smart food, feed, and bioenergy crop, adapted worldwide to temperate and tropical climates. Sustained gains in plant breeding rely on variation in crop gene pool. Over 231,000 sorghum accessions are conserved globally, with the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) genebank holding 39,234 accessions from 93 countries. Representative subsets in the form of core and mini core collections and reference sets have been developed and used to identify new sources of variations for stress resistance, phenology, seed yield and quality, and for bioenergy traits. Ethnolinguistic diversity, human migration, and social boundaries have shaped the abundant diversity among landraces, which significantly impacted conservation and distribution of on-farm diversity. Sorghum is a genomic resources rich crop. Genome-wide association mapping unraveled many significant marker–trait associations: flowering, plant height, tillering, culm length, inflorescence architecture, number of panicles, panicle length, seed weight, and stalk sugar; resistance to anthracnose, grain mold, and rust; increased seed yield under P-deficient or Al-toxic soils; or seed quality, with many of these markers comapped on the same linkage groups previously reported as harboring quantitative trait loci (QTL) or candidate genes associated with some of these traits. The sequencing of diverse sorghum germplasm and its comparison with a reference genome has revealed substantial untapped diversity, which offers a great opportunity for the genetic improvement of sorghum. Targeting Induced Local Lesions IN Genome (TILLING) populations unraveled new variations not previously known in sorghum. Genomic tools and information are being applied to harness new sources of variations by using S. halepense and S. propinquum to adapt sorghum to extreme climatic conditions, both in tropical and temperate regions.