It is important to recognize, particularly when speaking historically, that the work of the engineer and of the profession of engineering is not the same as the work of the scientist. Not is the work fully covered by the term "Applied Science" since the engineer has been, and still is, called upon to design products for which the science is not fully understood. And matters of definition are further complicated by the fact that engineering in some countries is a trade as well as a profession, and also the term 'technology, is often used interchangeably with engineering.