Enginners:

An engineer is a person professionally engaged in a field of engineering. Engineers are concerned with developing economical and safe solutions to practical problems, by applying mathematics and scientific knowledge while considering technical constraints.[1][2] As such, the work of engineers is the link between perceived needs of society and commercial applications. Some consider this profession to be the link between art and science.
In addition to machine design, machine research, and machine development, many engineers work in production, testing, or maintenance. These engineers determine the causes of component failure, supervise production in factories, and test the manufactured products to maintain the quality of said product.
Also, engineers estimate the time and cost to complete projects. Some move into engineering management or into sales. In sales, an engineering background enables them to discuss technical aspects and assist in the planning of products, installation, and use. Supervisory engineers are responsible for entire projects or major components.[2
In some countries of Continental Europe and Latin America and also in Turkey, the title is limited by law to people with an engineering degree, and the use of the title by others (even persons with much more work experience) is illegal. In Italy the title is limited to people who, besides holding an engineering degree, have passed a professional qualification examination (Esame di Stato). In Portugal, professional engineer titles and accredited engineering degrees are regulated and certified by the Ordem dos Engenheiros. In the Czech Republic the title "engineer" (Ing.) is given to people with a (master) degree in chemistry, technology or even economics (due to historical reasons and tradition). In Greece the title of Engineer is given only to those who have a Diploma, after five-year scientific studying in Engineering University faculties. It is considered a high-level title.