Engineers can be broadly classified as those who create things and those who operate them so that they can fulfill the purpose for which they were made. The former utilize their knowledge to its fullest extent in order to create things that satisfy specific objectives. On actual sites, the latter operate those things that the former engineers have created in order to fulfill their purpose under certain environmental conditions. And, the greater the target of management becomes, the more the system needs to be composed of multiple elements, which include a wide variety of wisdom and knowledge.