From CryptoDox, The Online Encyclopedia on Cryptography and Information Security
Interoperability is a property referring to the ability of diverse systems and organizations to work together (inter-operate). The term is often used in a technical systems engineering sense, or alternatively in a broad sense, taking into account social, political, and organizational factors that impact system to system performance.
(Interop is also the name of several annual networking product trade shows.)
The IEEE defines interoperability as:
the ability of two or more systems or components to exchange information and to use the information that has been exchanged.<ref>Institute of Electrical and Electronics Engineers. IEEE Standard Computer Dictionary: A Compilation of IEEE Standard Computer Glossaries. New York, NY: 1990.</ref>
In telecommunication, the term can be defined as:
Source: from Federal Standard 1037C and from the Department of Defense Dictionary of Military and Associated Terms in support of MIL-STD-188.
In two-way radio, interoperability is composed of three dimensions:
With respect to software, the term interoperability is used to describe the capability of different programs to exchange data via a common set of business procedures, and to read and write the same file formats and use the same protocols. (The ability to execute the same binary code on different processor platforms is 'not' assumed to be part of the interoperability definition!) The lack of interoperability strongly implies that the described product or products were not designed with standardization in mind. Indeed, interoperability is not taken for granted in the non-standards-based portion of the computing and EDP world.
According to ISO/IEC 2382-01, Information Technology Vocabulary, Fundamental Terms, interoperability is defined as follows: "The capability to communicate, execute programs, or transfer data among various functional units in a manner that requires the user to have little or no knowledge of the unique characteristics of those units". 
This definition focuses on the technical side of interoperability, while it has also been pointed out that interoperability is often more of an organizational issue. In other words, interoperability frequently has a major impact on the organization concerned, including issues of ownership (do people want to share their data?), staff (are people prepared to undergo training?) and usability. In this context, a more apt definition is captured in the term "business process interoperability".
Interoperability can have important economic consequences, such as network externalities. If competitors' products are not interoperable (due to causes such as patents, trade secrets or coordination failures), the result may well be monopoly or market failure. For this reason, it may be prudent for user communities or governments to take steps to encourage interoperability in various situations. In the United Kingdom, for example, there is an eGovernment-based interoperability initiative called e-GIF. As far as user communities, Neutral Third Party is creating standards for business process interoperability. Another example of a neutral party is the RFC documents from the Internet Engineering Task Force (IETF).
New technologies are being introduced in hospitals and labs at an ever-increasing rate, and many of these innovations have the potential to interact synergistically if they can be integrated effectively. The need for “plug-and-play” interoperability – the ability to take a medical device out of its box and easily make it work with one’s other devices – has attracted great attention from both healthcare providers and industry. <p>Interoperability helps patients get the most out of technology, and it also encourages innovation in the industrial sphere. When different products can be combined without complicated and expensive interfaces, small companies can enter a field and make specialized products. Without interoperability, hospitals are forced to turn to large vendors that provide suites of compatible devices but that do not specialize in any one area. Interoperability promotes competition, and competition encourages innovation and quality. <p>From the perspective of Intel, a major producer of consumer healthcare devices, there are six major factors that affect an industry’s ability to achieve interoperability. First there needs to be a demand for interoperable products. Second, there must be standards, or rules, defining what interoperability means in the field. Third, business conditions must encourage manufacturers to make their products interoperable. Fourth, guidelines must exist that make the often-complicated standards easier for companies to interpret. Fifth, compliance must be verified by independent testing; and finally, interoperability must be actively promoted. The rapid rise of wireless technology illustrates that interoperability is attainable. <p>Conditions in the biomedical industry are still in the process of becoming conducive to the development of interoperable systems. A potential market of interested hospitals exists, and standards for interoperability are being developed. Nevertheless, it seems that current business conditions do not encourage manufacturers to pursue interoperability. Only sixteen to twenty percent of hospitals, for example, use electronic medical records (EMR). With such a low rate of EMR adoption, most manufacturers can get away with not investing in interoperability. In fact, not pursuing interoperability allows some of them to tout the inter-compatibility of their own products while excluding competitors. By promoting EMR adoption, companies such as Intel hope to create an environment in which hospitals will have the collective leverage to demand interoperable products.
<p>In the medical industry, the need for interoperability is becoming severe. New technologies are being introduced at an ever-increasing rate. Many hospitals, for example, are now adopting electronic medical records, which promise to allow physicians to access more information with greater speed. In addition to electronic medical records, hospitals are continually introducing new imaging and therapeutic devices, many of which have the potential to interact synergistically if they can be integrated effectively. <p>The need for “plug-and-play” interoperability in a hospital setting has attracted great attention from both healthcare providers and from the biomedical industry. Hospitals and HMO’s form a large market for interoperable products, and standards defining interoperability in the medical sphere are being developed by a variety of international organizations such as IHE. Despite this interest, however, many manufacturers currently avoid investing in interoperability, touting the inter-compatibility of their own products while attempting to exclude competitors. <p>Leaders of hospitals and healthcare organizations are slowly realizing that achieving interoperability would greatly improve healthcare. Interoperable technology enables doctors to work more efficiently, and it helps prevent mistakes. Interoperability also encourages innovation in the industrial sector by allowing small companies to introduce specialized products. Without interoperability, hospitals are forced to turn to a few large vendors. Interoperability promotes competition, and competition encourages innovation and quality. As large hospitals begin to understand this fact, efforts to promote biomedical interoperability are gathering strength.
Interoperability is an important issue for law enforcement, fire fighting, EMS, and other public health and safety departments, because first responders need to be able to communicate during wide-scale emergencies. Traditionally, agencies could not exchange information because they operated widely disparate hardware that was incompatible. Agencies' information systems such as computer-aided dispatch systems (CAD) and records management systems (RMS) functioned largely in isolation, so-called "information islands." Agencies tried to bridge this isolation with inefficient, stop-gap methods while large agencies began implementing limited interoperable systems. These approaches were inadequate and the nation's lack of interoperability in the public safety realm become evident during the 9/11 attacks on the Pentagon and World Trade Center structures. Further evidence of a lack of interoperability surfaced when agencies tackled the aftermath of the Hurricane Katrina disaster.
In contrast to the overall national picture, some states, including Utah, have already made great strides forward. The Utah Highway Patrol and other departments in Utah have created a statewide data-sharing network using technology from a company based in Bountiful, Utah, FATPOT Technologies.
The U.S. government is making a concerted effort to overcome the nation's lack of public safety interoperability. The Department of Homeland Security's Office for Interoperability and Compatibility (OIC) is pursuing the SAFECOM and CADIP programs, which are designed to help agencies as they integrate their CAD and other IT systems.
The OIC launched CADIP in August 2007. This project will partner the OIC with agencies in several locations, including Silicon Valley. This program will use case studies to identify the best practices and challenges associated with linking CAD systems across jurisdictional boundaries. These lessons will create the tools and resources public safety agencies can use to build interoperable CAD systems and communicate across local, state, and federal boundaries.
Interoperability can be achieved in four ways: through product engineering, industry/community partnership, access to technology and IP, and implementation of standards.
Interoperability as a question of power and market dominance
Interoperability tends to be regarded as an issue for experts and its implications for daily living are sometimes underrated. The case of Microsoft vs. the European Commission shows how interoperablity concerns important questions of power relationships. In 2004, the European Commission found that Microsoft had abused its market power by deliberately restricting interoperability between Windows work group servers and non-Microsoft work group servers. By doing so, Microsoft was able to protect its dominant market position for work group server operating systems, the heart of corporate IT networks. Microsoft was ordered to disclose complete and accurate interface documentation, which will enable rival vendors to compete on an equal footing (“the interoperability remedy”). As of June 2005 the Commission is market testing a new proposal by Microsoft to do this, having rejected previous proposals as insufficient.
Recent Microsoft efforts around interoperability may indicate a shift in their approach and level of commitment to interoperability. These efforts including the migration of Microsoft Office file formats to ECMA Office Open XML, and several partner interoperability agreements, most notably their recent collaboration agreement with Novell.
Interoperability has also surfaced in the Software patent debate in the European Parliament (June/July 2005). Critics claim that because patents on techniques required for interoperability are kept under RAND (reasonable and non discriminatory licensing) conditions, customers will have to pay license fees twice: once for the product and, in the appropriate case, once for the patent protected programme the product uses.