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. In information technology, systems integration is the process of linking together different computing systems and software applications physically or functionally, to act as a coordinated whole. It is an IT or engineering process or phase concerned with joining different subsystems or components as one large system.
SI is also used to add value to a system through new functionalities provided by connecting functions of different systems. It ensures that each integrated subsystem functions as required.
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. The physical components consist of the various machine systems, computer hardware, inventory, etc. The virtual component consists of data stored in databases, software, and applications.