Haploid plants with a doubled set of chromosomes (doubled haploid (DH)) significantly speed up the selection process by the fixation of genetic traits in each locus in the homozygous state within one generation. Doubled haploids are mainly attained by the formation of plants from the cultured gametophytic (haploid) tissues and cells in vitro, or by targeted reduction in the parent chromosome during intra- or interspecific hybridization. Since then, DH has become one of the most powerful tools to support various basic research studies, as well as applied research. This review is focused on the recent development of the production of doubled haploids in vivo and their fundamental bases. The various mechanisms and approaches responsible for the formation of haploids in vivo are discussed, particularly the induction of parthenogenesis by BBM-like proteins, the long constructed Salmon system of wheat, the usage of patatin-like phospholipases MTL/PLA1/NLD, the IG1 system, uniparental genome elimination during interspecific hybridization, and the perspective technology of centromeric histone 3 (CENH3) modification.