Mutation is the heritable change to the genetic material; individuals that manifest modified characteristics on account of heritable changes are known as mutants. In nature, the combinations of the errors that occur during the replication of deoxyribonucleic acid (DNA) and damages to this hereditary material on account of an individual’s exposure to sunlight and ultra-violet (UV) radiation and diseases lead to heritable changes to the genetic blueprint. Other types of mutations include duplications whereby whole parts of the genome are doubled and translocations whereby a part of a chromosome is transferred to a non-homologous chromosome; these occur as a result of errors during meiotic cell division. Their effects depend on whether or not, and how, genes are affected in such mutations. The accumulations of such aberrations have been the primer for evolution and speciation. Stretches of DNA make up the basic unit of heredity, the gene. The subtle changes to DNA sequences are the most useful for crop improvement as the more gross alterations (at the chromosomal and cellular levels) invariably confer some levels of unfitness and even lethality. One way for classifying mutations at the DNA sequence level is to categorize the mutation on the basis of how the modification affects the gene’s ability to synthesize the protein that it is responsible for. In general, the mutations that are important in crop improvement usually involve single bases and may or may not affect protein synthesis.