Open systems are computer systems that provide either interoperability, portability, or freedom from proprietary standards, depending on your perspective.

For years the term was applied loosely to the many flavors of Unix. Since the emergence of The Open Group's Single UNIX Specification, any operating system that supports the Unix APIs (z/OS, for example) can reasonably be classed as an open system.

See Also

• Open standard
• Unix wars
• Open system in systems theory