Publicly maintained, readily available standards that are not owned or specified by a single commercial organisation and so can be used widely.
Specifications that are public-that is, not owned by any company or individual. The Internet is based on open standards.
Computing specifications that are public, not proprietary. Open standards enable greater interoperability between applications, both within and beyond an organisation.
The goal behind open (product-independent) standards initiatives for information formats such as Standard Generalized Markup Language (SGML), Extensible Markup Language (XML), and Hypertext Markup Language (HTML), is not that of creating structured, i.e. restrictive, information standards. The Open Standards movement looks for ways of providing forums to discuss and promote interoperability standards; and to recommend ways of extending and improving interoperability among users.
Open standards are publicly available specifications that provide a common method of achieving a particular goal. HTML and CSS are open standards, and the popularity of these illustrates the importance of open standards and how they encourage interoperation between hardware and software platforms.
Standards not owned by any company.
A standard with publicly available specifications, which can be implemented by any developer. Open standards are typically developed and maintained by a review process in which all interested parties may participate, in contrast to proprietary standards, which are developed and maintained by a single company.
Making a standard available to anyone, this means that there will be much higher support, and the possibility of systems that can easily interact.
Standards that are widely used, consensus based, published and maintained by recognized industry standards organizations.
"Open standards future proof guidelines or specifications approved by a recognized standards organization and has been or is accepted as a de facto standard by the industry. Standards exist for programming languages, operating systems, data formats, communications protocols, and electrical interfaces. Standard are very important for developers and managers who have to decide to choose e.g. a new e-learning platform. If the platform is 'standard-proof' you can move your content from and into that platform. Well known standards relevant to e-learning are IEEE, IMS, ISSS et cetera."
Open Standards are recognised national or international platform independent standards. They are developed collaboratively through due process, are vendor neutral, do not rely on commercial intellectual property.
Wikipedia Definition: Open Standards