Systems engineering is an interdisciplinary approach and means to enable the realization of successful systems (International Council on Systems Engineering, INCOSE).
Systems engineering is an interdisciplinary approach that defines the complete set of technical and managerial efforts required to transform a set of customer needs, expectations, and constraints into a solution and to support that solution throughout its life (ISO/IEC/IEEE 24765:2010).
The purpose of systems engineering is to guide the development of complex, integrated systems. A system is defined as a set of interrelated components that work together to achieve a common goal. A complex engineering-intensive system consists of several heterogeneous, diverse elements that are interconnected in a complex manner and requires the application of systems engineering to guide its development.
Systems engineering differs from traditional disciplines in that its subject is the system as a whole: it is concerned with customer needs and operating conditions, it directs the development of the system concept, it bridges traditional engineering disciplines, and it overcomes misunderstandings among individual specialists.
Systems engineering is an integral part of project management, as it is necessary for planning and directing engineering efforts.