A descriptive account on systems engineering has been provided in this book, elucidating the theoretical as well as practical approaches. It is a compilation of research works contributed by researchers and developers from all over the world. A majority of these works elucidate methodologies for distinct systems engineering procedures while others consider matters of parallel knowledge areas and sub-areas which essentially contribute to the enhancement, maintenance and operation of systems. This book consists of data on spacecraft, aircraft and space systems development, post-analysis of information gathered during working of huge systems, etc. Important matters regarding "bottlenecks" of systems engineering, like security, complexity and authenticity of various types of systems, creation, operation and maintenance of services, system-human communication and management tasks done during system projects have been addressed in this book. It is very useful for those who are interested in the modern state of the systems engineering information field and for systems engineers engaged in various activities of the field. The aim of this book is to serve as a valuable source of reference for students and university lecturers. It can be directly used in systems engineering courses as descriptive materials.