There are various definitions of Open Standards, such as the definitions in the European Commission European Interoperability Framework (EIF) , the motion B 103 of the Danish Parliament , the definition by Bruce Pehrens , the definition developed by the SELF Consortium , the one by the Spanish Estandares Abiertos  and the Foundation for a Free Information Infrastructure's recommendations on the EIF 2.0 . Orienting itself along the lines set of the above initiatives, we understand Open Standards as follows.
The following are the minimal characteristics that a specification and its attendant documents must have in order to be considered an open standard:
- The standard is adopted and will be maintained by a not-for-profit organisation, and its ongoing development occurs on the basis of an open decision-making procedure available to all interested parties (consensus protection of privacy in the electronic communications sector or majority decision etc.).
- The standard has been published and the standard specification document is available either freely or at a nominal charge. It must be permissible to all to copy, distribute and use it for no fee or at a nominal fee.
- The intellectual property - i.e. patents possibly present - of (parts of) the standard is made irrevocably available on a royalty-free basis.
- There are no constraints on the re-use of the standard.
- However, the first condition does not have to be fulfilled in the case that a complete reference implementation of the specification exists in Free Software (a.k.a Open Source or Libre Software), i.e. under a license approved by either the FSF  or OSI .
In line with this definition the need for the use of Open Standards is based in the following main reasons:
- Open Standards guarantee interoperability, in other words, they allow the exchange of information independent of the software that is used. Therefore, Open Standards are a precondition for technological neutrality.
- Open Standards guarantee that the information digitally generated in a certain moment in time will be readible and reusable in the next milleniums. This is independent of the fact whether the programs used for its generation will be still available or not in the future. Thus, public and open specifications guarantee the preservation, durability, integrity and reusability of the information without restrictions.
- Open Standards allow for a level playing field for all software developers, which favours competition in the market, stimulates innovation, while at the same time drives costs down.
- Open Standards facilitate the interaction of citizens with public administrations and private entities, as they don't impose any particular software vendor. A company or citizen who uses a software based on Open Standards will never find itself forced to acquire a competing software of the one the are already using, to exercise the right to communicate with their public administration.
- Free Software tends to use and help define Open Standards, since it consists by definition of publicly available specifications, and the availability of its source code promotes an open, democratic debate around the specifications, making them both more robust and interoperable.
 IDABC's European Interoperability Framework, http://ec.europa.eu/idabc/en/document/3473#finalEIF
 Motion B of the Danish Parliament, http://www.ft.dk/Samling/20051/beslutningsforslag/B103/index.htm
 Bruce Pehrens definition of Open Standards, http://perens.com/OpenStandards/
 Science, Education and Learning in Freedom (SELF), definition of Open Standards, http://selfproject.eu/en/OSD.html
 Estandares Abiertos definition of Open Standards in Spanish, http://www.estandaresabiertos.com//index.php?option=com_content&task=view&id=24&Itemid=33
 Foundation for a Free Information Infrastructure's Ten Recommendations on the EIF 2.0, https://action.ffii.org/eif
 Free Software licenses approved by the Free Software Foundation, http://www.fsf.org/licensing/licenses/
 Open Source licenses approved by the Open Source Initiative, http://www.opensource.org/licenses/