Molecular markers are becoming essential tools in many areas of biology including bio-medicine, breeding, forensics and diversity analysis. In addition they are also being exploited to locate and isolate genes of interest. A variety of DNA based molecular marker techniques are now available. Individual techniques employ different methods used routinely in molecular biology and different kinds of markers are distinguished by their capacity to detect polymorphism at one or many loci and whether they are dominant or co-dominant markers. The choice of marker system will depend on individual laboratory facilities and the applications of interest to each researcher.