Abstract: Genetic markers are useful in identification of various genetic variations. The development of DNA-based genetic markers has had a revolutionary impact on genetic studies. With DNA markers, it is theoretically possible to observe and exploit genetic variation in the entire genome. These markers can be used to study the evolutionary relationships among individuals. Popular genetic markers include allozymes, mitochondrial DNA, RFLP, RAPD, AFLP, microsatellite, SNP, and EST markers. The application of DNA markers has allowed rapid progress in investigations of genetic variability and inbreeding, parentage assignments, species and strain identification, and the construction of high-resolution genetic linkage maps for aquaculture species. The advent of next-generation sequencing (NGS) has revolutionized genomic and transcriptomic approaches to biology. The new sequencing tools are also valuable for the discovery, validation and assessment of genetic markers in populations. This review focuses on importance and uses of genetic markers with advent of modern technologies.