Global Information Grid
Conceptually, the Global Information Grid (GIG) is the set of resources, personnel, procedures and technologies that provide end-to-end information sharing among all elements of the U.S. Department of Defense, other U.S. government agencies, and allies. In practice, the GIG focuses more on interconnecting fixed installations, and semi-mobile facilities such as the command centers of larger tactical units. It is a fundamental tool for staff operations. It uses a distributed computing paradigm, more for data replication and distribution rather than parallel computation on single problems.
While it is true to think of GIG as interconnecting everything, the practical distinction is that the "true" GIG runs over fixed, high-capacity, high-reliability communications networks. Operational networks among mobile units are at the "edge" of the GIG. These tactical networks, such as the Joint Tactical Information Distribution System, or ad hoc networks set up with radios in individual airplanes, tanks, and even soldiers' individual handhelds, are much more constrained in capacity and reliability. The Joint Tactical Radio System, for example, deals with constraints imposed by geography, by limited electrical power, and by deliberate enemy electronic warfare.
In contrast, GIG services tend to run over the some of the networks, of different security levels, which are overlaid on the shared Defense Information System Network. Examples of overlay networks are NIPRNET for unclassified but not public information, SIPRNET for information through the basic SECRET level, and JWICS for material above SECRET or with other compartmented control system restrictions.
There is also an increasing and challenging requirement for communications among multinational forces and coalitions: Coalitions can be composed of diverse groups of security and information sharing environments. Multinational forces may have differences in their communications system, language, terminology, doctrine, and operating standards that can cause confusion and interoperability problems in an operational environment.  
Certain multinational groupings, such as the "quadripartite" of Australia, Canada, the United Kingdom, and the United States, have a very high level of trust. There is still significant trust in a multinational treaty organization such as NATO. Even when there is limited trust, countries and organizations that recognize they may need to work together in specific situations, such as NATO and the Soviet Union, have proposed to establish interoperable communications between their airborne warning and control systems (AWACS), the E-3 Sentry and the Beriev A-50.
Above all, components must be interoperable, emphasizing standards-based compatibility so that they can be transformed into the information systems needed by particular users in particular situations, whether those needs were predicted or a total surprise.
The system must be trusted, in terms of availability and security. 
Remembering that GIG includes communications as well as computing, it has seven system components. . Without the first, the "warrior component", the others have no meaning; they are there to support the warriors.
The seven GIG communications system components are:
- global applications,
- network operations (NETOPS)
- information management
These are the edge networks that directly connect to the "personal, shipboard, track-, vehicle-, and aircraft-mounted radios, computers, software, and display devices that directly contribute to situational awareness, collaboration, and access to information critical to combat operations to the decision maker/shooter"
Global Applications Component
The global applications component is the set of information applications used by the joint force over the GIG, and which run on the computing component. It provides the information needs of the force and includes applications in areas such as fire support, weather, logistics, medical, and business.
Representative applications include:
- Army Battle Command System (ABCS)
- Defense Collaboration Tool Suite (DCTS): An interoperable, real time asynchronous collaboration capability that includes voice and video conferencing, document and application sharing, instant messaging, virtual meeting, and whiteboard capability
- Defense Message System (DMS): the Defense Department electronic mail system
- Global Command and Control System (GCCS) for the Joint Chiefs of Staff and Unified Combatant Command commanders. A major subcomponent is the Joint Operation Planning and Execution System (JOPES).
- Global Command and Control System-Maritime for the United States Navy
- Theater Battle Management Core System (TBMCS), for air and missile operations at the level of a geographic Unified Combatant Command. This system helps create and disseminate the air tasking order (ATO). 
The computing component includes both DISA defense enterprise computing centers (DECCs), as well as procurement and support of field computers, displays, and system software.
These are the actual core communications systems that connect bases, through the fixed strategic network, to the "first tactical mile" of the warrior component. The strategic networks need leasing and construction of global optical networks, leasing or operation of communications satellites, etc. Electromagnetic spectrum management is essential for the tactical networks, and for the wireless strategic networks.
Network Operations Component
Abbreviated NETOPS, this component operates the technical components of computers and communications networks. NETOPS also defends the GIG against miscreants attacking the computing systems and data, and against electronic warfare against the communications network.
The responsibility for NETOPS is under United States Strategic Command, delegated to the "joint task force, global network operations", which is primarily another name for the Defense Information Systems Agency with support from the information assurance capabilities of the National Security Agency.
Information Management Component
This component is concerned with making sure that the right people have access to the information they need, in a timely manner and useful format. It also gives them tools to work with the information, variety of common information sharing services such as messaging, search engines, collaboration software (e.g., Intellipedia and other non-public wikis) and directory services; these tools are managed and assured through the NETOPS component.
This is the overall policy, contractual, international agreement, and procedural structure that make the human components work together. The "strategic, operational, tactical, and base/post/camp/station/shipboard" technical components are only there to support the function of people.
- Joint Communications System, March 20, 2006, Joint Publication 6-0
- JP 6-0, pp. III-5 to III-6
- Multinational Operations, March 7, 2007, JP 3-16
- Federation of American Scientists, Beriev A-50 Mainstay
- JP 6-0, pp. I-8 to I-11
- JP 6-0, pp. A-1 to A-8
- Joint Publication JP 3-30: Command and Control for Joint Air Operations, 5 June 2003 p. III-28
- Air Land Sea Applications Center, U.S. Army Training & Doctrine Command (April 1999), Multiservice Procedures for Joint Task Force Information Management (JTF-IM), FM 101-4/MCRP 6-23A/NWP 3-13.1.16/AFTTP(I) 3-2.22