Haploids are plants (sporophytes) that contain a gametic chromomosome number (n). They rarely occur spontaneously in nature but several techniques are nowadays available for their production. ...Induction and regeneration of haploids (doubled haploids) enables the production of completely homozygous lines in one generation, thus shortening this process by many years. They are broadly used in breeding programs of plant species for which efficient protocols have been developed, such as barley, wheat, maize, tobacco, onion, cucumber, rapeseed and other Brassica species. This article presents the main characteristics of haploids, doubled haploids and inducing techniques, with an emphasis on their role in plant breeding.