PPI has produced a number of definitions of systems engineering at different levels of abstraction and for use in different contexts. One PPI answer to the question ‘what is systems engineering?’ follows.

Systems engineering is a set of principles and supporting methods, based on systems thinking, for the successful engineering of solutions to problems.

The approach is based on process elements that are selected and integrated for use in response to a given set of circumstances, with the aim of maximizing the value delivered to applicable stakeholders, and having regard to uncertainty. 

Mastery of systems engineering spans requirements analysis (requirements capture and validation), physical (structural) design, logical design, effectiveness evaluation and decision making (the conduct of trade studies), specification of system elements, system integration (building the system in development), verification of work products (job right?), validation of work products (right job?), integration of specialty engineering disciplines, and systems engineering management. 

Together these process elements, applied recursively and with degrees of iteration dependent on novelty, complexity and stability of need, embrace the totality of systems engineering practice, when applied to socio-technical and technical systems, including systems for development, production, maintenance, retirement, disposal, and other system life cycle processes, as applicable.