"The aim of a World Register of Marine Species (WoRMS) is to provide an authoritative and comprehensive list of names of marine organisms, including information on synonymy. While highest priority goes to valid names, other names in use are included so that this register can serve as a guide to interpret taxonomic literature. The content of WoRMS is controlled by taxonomic experts, not by database managers. WoRMS has an editorial management system where each taxonomic group is represented by an expert who has the authority over the content, and is responsible for controlling the quality of the information. Each of these main taxonomic editors can invite several specialists of smaller groups within their area of responsibility to join them. This register of marine species grew out of the European Register of Marine Species (ERMS), and its combination with several other species registers maintained at the Flanders Marine Institute (VLIZ). Rather than building separate registers for all projects, and to make sure taxonomy used in these different projects is consistent, VLIZ developed a consolidated database called ‘Aphia’. A list of marine species registers included in Aphia is available below. MarineSpecies.org is the web interface for this database. The WoRMS is an idea that is being developed, and will combine information from Aphia with other authoritative marine species lists which are maintained by others (e.g. AlgaeBase, FishBase, Hexacorallia, NeMys). Resources to build MarineSpecies.org and Aphia were provided mainly by the EU Network of Excellence ‘Marine Biodiversity and Ecosystem Functioning’ (MarBEF), and also by the EU funded Species 2000 Europe and ERMS projects. Intellectual property rights of the European part of the register is managed through the Society for the Management of Electronic Biodiversity Data (SMEBD). Similar solutions are now being investigated for the other parts of the register. Aphia contains valid species names, synonyms and vernacular names, and extra information such as literature and biogeographic data. Besides species names, Aphia also contains the higher classification in which each scientific name is linked to its parent taxon. The classification used is a ‘compromise’ between established systems and recent changes. Its aim is to aid data management, rather than suggest any taxonomic or phylogenetic opinion on species relationships. Keeping WoRMS up-to-date is a continuous process. New information is entered daily by the taxonomic editors and by the members of our data management team. Often data also come in from contributions of large datasets, such as global or regional species lists. No database of this size is without errors and omissions. We can’t promise to make no errors, but we do promise to follow up and give feedback on any communications pointing out errors. Feedback is very welcome!"