In engineering, system integration is defined as the process of bringing together the component subsystems into one system and ensuring that the subsystems function together as a system.[1] In information technology, systems integration[2] is the process of linking together different computing systems and software applications physically or functionally,[3] to act as a coordinated whole.
The system integrator brings together discrete systems utilizing a variety of techniques such as computer networking, enterprise application integration, business process management or manual programming.[4]
Systems integration has traditionally been a crucial specialty in the defense contracting industry. Proprietary, closed systems needs to be upgraded or, as is often the case, legacy hardware or software must be preserved within modern computing networks, graphical user interfaces (GUIs) or hardware connection standards.