Nucleic acid sequencing is one of the most important tools of biological research with very broad application. Four generations of DNA sequencing technologies can be distinguished by their nature and the kind of output they provide. Sanger sequencing dominated for 30 years and was the workhorse of the Human Genome Project. In 2005 the first 2nd generation sequencer was presented with an output orders of magnitude higher than Sanger sequencing and dramatically reduced cost per base. Currently, we are at the dawn of third generation with nanopore systems that are being developed for DNA sequencing. Meanwhile, the field is broadening applications that complement first, second and third generation sequencing systems to get high-resolution genetic information and fourth generation sequencing is on the horizon. Second generation nucleic acid sequencers are systematically applied in many large-scale international projects such as the International Cancer Genome Consortium and the International Human Epigenome Project.
