open
adj.
Available and accessible; without restrictions; not closed.
ComputingProprietary, but available to other developers.
ComputingVendor neutral.
ComputingPublished under terms of the General Public License or a similar agreement.
ComputingCollaboratively developed, especially by volunteers.
Maintained by and available from a government or standards organization.
Notes
Open1 is the opposite of closed, restricted, or classified. - Within computing, open2-5 has many meanings that vary with context and use. In general, it is used as an antonym of closed, which refers to proprietary software and hardware that is a black box to all but the developer. A closed system has defined inputs and outputs, but without additional information about the system it is impossible to make that system do anything else. An open system exposes its internal workings, allowing others to understand how the system works. In principle, others can then interact with, modify, or add to the system. In practice, licensing agreements may restrict what can be done with an open system. For example, it may be permissible to build components that connect to an open hardware system, but not to reproduce the system itself.
Citations
Schmelzer 2003 The word 'open' has no commonly accepted meaning in the phrase 'open standard.' For many organizations, 'open' means that they aren't the only organization that supports the advancement and development of a given technology. However, this is an all-too-broad definition that puts Microsoft's .NET in the same camp as Java – since there are millions of developers for each of those platforms. For others, a standard is open only if a vendor-neutral third-party organization (or even governmental body) creates and manages it. However, this definition is too strict in that it excludes the term 'open source' from its meaning. Finally, many organizations consider a standard to be 'open' if the specification has merely been published for review.