An engineer is a professional practitioner of engineering, concerned with applying scientific knowledge, mathematics, and ingenuity to develop solutions for technical, societal and commercial problems. Engineers design materials, structures, and systems while considering the limitations imposed by practicality, regulation, safety, and cost. Science is knowledge based on observed facts and tested truths arranged in an orderly system that can be validated and communicated to other people. Engineering is the creative application of scientific principles used to plan, build, direct, guide, manage, or work on systems to maintain and improve our daily lives. The word engineer is derived from the Latin words ingeniare (“to contrive, devise”) and ingenium (“cleverness”). The work of engineers forms the link between scientific discoveries and their subsequent applications to human needs and quality of life.