To begin with, the tremendous quantities of species and the considerably bigger size of few genomes make the entire sequencing of all genomes, a non-ideal approach for understanding genome structure. Second, within a given species most people are genetically distinct in various ways. What does it really mean, for instance, to "sequence a human genome"? The genomes of two people who are hereditarily distinct differ with respect to DNA sequence. These two issues, and the potential for other novel applications, have offered ascend to new methodologies which, taken together, constitute the field of relative genomics. Agriculture is the field that receives the rewards of comparative genomics. Recognizing the loci of favorable genes is a key stride in rearing harvests that are enhanced for greater yield.