The prediction of double helical structure of DNA by Watson and Crick opened a whole new world of genomics. Genomics deals with the study of gene sequence and expression in the DNA of an organism. Genomics also deals with the comparison of gene expression among individuals from same or different species, genera or kingdom. The four unique bases (adenine, guanine tyrosine and cytosine) that make a DNA molecule hold the master key to all the many new techniques that have been devised for rapid gene sequencing in last two decades. Among them the most reliable and simple methodology involves the method devised by Maxam and Gilbert, 1980. The beauty of the method lies in end labeling one of the DNA fragments after cleaving at each of the four specific bases in four different reactions. These cleaved products are then separated using denaturing polyacrylamide gels according to their size. Subsequently the sequence can be read directly from an autoradiogram by determining which of the base specific reagents cleaved adjacent nucleotides. Hence the methodology includes isolation of defined DNA fragments, end labeling of the DNA fragments, separation of the two-labeled ends of a DNA fragment followed by base specific chemical cleavage. This method can be combined with method for specific recognition of DNA sequences by Southern blotting (Southern, 1975). DNA sequencing has helped in predicting gene functions under various environmental conditions like biotic and abiotic stress conditions etc. This will in turn help in engineering plants and microorganisms for specific characters as per the need and betterment for mankind.