**1. Introduction**

Mutation breeding also called "variation breeding," is the procedure of exposing seeds to chemicals or radiation to produce mutants with desirable traits. The mutants created are called mutagenic plants or mutagenic seeds and can be used directly as a commercial cultivar or used as parent to breed new commercial cultivars. Although mutation breeding in the past fifty years was mainly focused on improving the yield specifically height reduction in wheat and rice, in contrast, today's challenges are environmental stresses and its related effects and to motivating for climate-smart agriculture for food security [1]. In this chapter, the historical background of mutation breeding has been discussed

chronologically. The types of mutants and mutations reported in worldwide literature are described. The natural and spontaneous mutations are elaborated with practical examples. All types of physical and chemical mutants and their success stories are discussed citing examples from all over the world. Lastly, the impact of mutation breeding on food security is explained with practical examples and achievements so far. The future prospectus of mutation breeding has also been discussed to highlight the significance of this important plant breeding process. This chapter provides a comprehensive understanding of the process with successful commercial examples of mutation breeding and the potential of this technique to meet future food security challenges. This chapter includes (i) introduction, (ii) historical background/development of mutation breeding (iii) mutation concept and its importance (iv) mutant crop varieties and their impact on food security (v) new breeding techniques (vi) prospects (vii)conclusions
