Broadly defined, engineering is the science-based profession by which the physical forces of nature and the properties of matter are made useful to humans in the form of structures, machines, and other products or processes at a reasonable expenditure of time and money. An engineer conceives, designs, creates, and implements apparatuses or processes to solve economic, environmental, or social problems. Engineering also is used to create or improve end products. This problem-solving profession requires the application of mathematical, scientific, and technical principles.

The various branches of engineering serve a wide range of industries. Electrical engineers, for example, design communications equipment, electric power plants, and computers and other electrical devices. Mechanical engineers deal with machines such as engines and motors as well as with manufacturing such equipment. An engineer working in one specialty usually requires some knowledge in associated fields, as most engineering problems are complex and interrelated. A mechanical engineer designing a power plant, for instance, must deal with materials, structures, and electrical equipment in addition to problems related purely to mechanical engineering. Major industrial work very often requires the talents of many engineers with different technical backgrounds and experiences.

The variety of activities in the field furthermore demands people with different levels of education and experience. Engineering encompasses the activities of professional engineers, engineering technologists, and technicians. While engineers deal with the advanced areas in which the latest tools of technology are required, tasks that require only well-established approaches may be performed by technologists. Technologists also play a key role in implementing engineering activities. Technicians normally perform more practical work in the shop or in the laboratory while following well-defined procedures.

Branches of Engineering

Engineering may be divided into a number of major traditional branches. The largest are electrical, mechanical, civil, industrial, and chemical engineering. There also exist several specialized areas that may be characterized as subfields of the major branches.

Aerospace Engineering

The design, modeling, development, manufacture, maintenance, testing, analysis, and use of aircraft, spacecraft, satellites, rockets, and missiles is the work of aerospace engineers. Engineers who work with aircraft are sometimes called aeronautical engineers, while those who work with spacecraft may be called astronautical engineers. The field requires knowledge of aerodynamics, structural design, propulsion equipment, controls, and electronic communications, or avionics. Astronautical engineers must also have a background in rocket propulsion and space navigation.

Biomedical Engineering, or Bioengineering

A relatively new field, biomedical engineering, or bioengineering, applies engineering principles to solve medical and biological problems. Uniting engineering and medicine, biomedical engineers work closely with medical personnel such as physicians, nurses, therapists, and medical technicians in the design and construction of medical instruments and advanced equipment used in modern hospitals. Bioengineers design artificial limbs, artificial hearts, and other organ substitutes and conduct fundamental research to solve clinical problems, such as the prevention, diagnosis, and treatment of diseases. Biomedical engineers must have a background in the biological sciences in addition to engineering.

Chemical Engineering

An especially diverse profession, chemical engineering deals with the large-scale production or conversion of chemicals for industrial use. Problems are usually divided into unit operations or unit processes such as distillation, evaporation, absorption, humidification or drying, adsorption, separation of various constituents, size reduction, mixing, and others. A knowledge of chemical reactions—and of the basic laws of conservation of matter and energy as well as those defining chemical equilibrium—is prerequisite to the understanding of most unit processes. The chemical engineer must be able to move from the laboratory to large-scale and economical industrial production by arranging all the unit operations in their proper sequence. Rather than processing a single batch of material at a time, continuous production is utilized in many modern plants for efficiency of operation. This is possible only when well-designed automatic controls have been incorporated in the plant.

Chemical engineers must apply principles of chemistry, physics, mathematics, and materials science, as well as of mechanical and electrical engineering. The duties of a chemical engineer overlap many fields.

Civil Engineering

One of the oldest of the engineering fields is civil engineering, which is concerned with structural works. It is very broad with many subspecialties, including structural, geotechnical, water resource, and transportation engineering. Structural engineers are concerned with the safe design and construction of structures. These can range from small warehouses to skyscrapers and from highway overpasses to large bridges and can include dams of all sizes. Geotechnical and soil mechanics engineers evaluate the capacity of rocks and soils to bear heavy structures. Water resource engineers handle water collection, distribution, and purification, including the building of dams, flood control, and irrigation. Transportation engineers design highway and public transportation systems.

Computer Engineering

A subspecialty that combines electrical engineering with computer science, computer engineering concerns all aspects of computer systems including the design, construction, implementation, and operation of hardware and software for personal and business computers. Some computer engineers specialize in areas such as digital systems, operating systems, computer networks, automation and controls, computer-aided design, and robotics. Computer engineers should possess a foundation in physics and mathematics as well as in electronics, programming, operating systems, data communications, and other related subjects.

Electrical and Electronic Engineering

Electrical engineering began with the production, distribution, and utilization of electric power. The design and manufacture of generators, motors, transmission systems, and their controls are all part of electric power engineering. With the invention of the vacuum tube in the early 20th century, electrical engineering branched into communications systems—including radio and television—or electronic engineering. The complex systems required to switch telephone calls and transmit data through satellite and optical fiber networks are responsibilities of communications engineers. Electric circuits, electronics, logic and switching, electrical machines, and communications systems are just a few areas with which the electrical engineer must be conversant.

Environmental Engineering

Environmental engineers are concerned with the safe and environmentally sound disposal and treatment of residential and industrial wastes and the protection of air and water quality. Global warming, automobile emissions, ozone depletion, acid rain, sustainable development, and alternative energy sources are all aspects with which these engineers are concerned. Environmental engineering is an interdisciplinary field that combines civil, chemical, and mechanical engineering and requires the application of biological and chemical principles.

Geological and Mining Engineering

The field of geological and mining engineering deals with the discovery and exploration of mineral deposits, the various processes to extract these minerals, and their conversion into useful metals or other refined products. Mining engineers are responsible for the safe, economical, and environmentally sound operation of coal, metal, and mineral mines. Petroleum engineering, a subspecialty of this field, is directed to the discovery of oil and gas sites and the economic recovery of these fuels. An understanding of geology, rock mechanics, extraction processes, and the behavior of ores and metals is required.

Industrial and Management Engineering

The efficient use of a modern factory—including the layout of machines, the best use of human labor, and the safe operation of the plant—fall into the domain of industrial engineers. They are also involved in quality control and inspection to check that the final product meets specifications. Production techniques, automation, statistics, operations research, and the interaction between human beings and machines (ergonomics) are some of the fields that need to be mastered by the industrial engineer. Management engineering is an extension that adds the role of management to complex technical processes.

Materials Engineering

The study and development of appropriate materials to meet various industrial needs is involved in materials engineering. If the emphasis is on metals, the term metallurgical engineer is generally applied. Materials engineering also covers the development of plastics (polymers), ceramics, semiconductors, and composite materials. Materials engineers investigate the properties and behavior of materials and apply principles of chemistry, mathematics, and physics to arrive at the best material solution to a particular problem. Often materials engineers work not forward but backward, to determine the particular reasons a material in service did not perform as expected.

Mechanical Engineering

Mechanical engineering encompasses the design, construction, and utilization of machines. These may be involved in the conversion of energy such as in the production of useful work from fuels. Automotive engines, gas turbines, and steam power plants fall into this category. The conversion of fluid and mechanical power in pumps, fans, propellers, and hydraulic turbines is another aspect.

Mechanical engineers also design machine components, such as the transmission, steering system, and brakes of a car. Mechanical design can involve large machines, such as presses or forges, or complex equipment such as textile machinery. Frequently it deals with the design of machines used to make other machines—the so-called machine tools, including computer-controlled lathes and milling machines. Air conditioning, refrigeration, ventilation, and the control of air pollution also fall into mechanical engineering, as does manufacturing engineering, or the making of parts and components (sometimes with the help of robots). The mechanical engineer must have knowledge of thermodynamics, fluid mechanics, heat transfer, machine design, vibrations, controls, and robotics. (See alsoautomobile industry; diesel engine; fan, electric; furnace and boiler; heat; heating and ventilating; internal-combustion engine; mechanics; refrigeration; steam engine; tools; turbine.)

Nuclear Engineering

The safe design and operation of nuclear power plants are the responsibilities of nuclear engineers. These engineers are concerned with shielding systems to safeguard people from the harmful effects of radiation and with the safe disposal of nuclear wastes. In addition to requiring a knowledge of nuclear physics, the field involves an understanding of materials that can withstand high temperatures and bombardment by nuclear particles as well as many aspects of mechanical engineering.

Functions of the Engineer

Many engineers are employed in industry, working in large manufacturing organizations. Their jobs differ significantly in such areas as design, construction, operations, and maintenance. The many different engineering functions include the following:


The research engineer tries to develop new principles and processes by using mathematics, scientific concepts, and experimentation. For instance, large computer simulations developed by research engineers permit the prediction of the performance of an airplane to the point that wind-tunnel and flight testing have been significantly reduced. Most research engineers hold advanced degrees, usually doctorates.


Complex engineering systems need long periods of time for their development. Involved are the designing of components, often using new materials or new ideas, the testing of these components, and then the improving of the original ideas. All of the components must then be put together to build the final engineering system. This often implies that the small-scale experiments performed by the researcher must be scaled upward to the level of industrial practice. The chemical engineer, for instance, must extend the findings of a laboratory experiment to a small pilot plant and, if successful, to full-scale production. Engineers engaged in development usually hold advanced degrees.


Coupled with and following development is design. An engineering project must not only work, but it must be safe, economical, and reliable and must meet the needs of the customer. The specific layout of an engineering product or structure becomes the responsibility of the design engineer.


Most engineering products must be fully tested before they can be delivered to a customer. Testing may show possible failures. The product then requires redesigning. Development, design, and testing must work closely together.

Manufacturing or Construction

The actual making of the parts, whether in a factory or by assembling a structure on-site, involves all the tools of production. The manufacturing engineer selects the right tools, schedules the flow of material and parts for the right machines, and supervises assembly.

Quality Control and Inspection

The quality control engineer checks that all raw materials, parts, assemblies, and products meet technical, and various other, requirements. Quality control engineers monitor and test the quality and safety of products throughout all stages of the manufacturing process.

Sales and Marketing

Interaction between the manufacturer and the customer is the responsibility of sales or marketing engineers. Frequently they may need to educate the customers. They must understand all the technical aspects of their products as well as the needs of their customers. These needs may require the addition of special features or even major redesign of a product. Thus the sales engineer must be in contact with all parts of the manufacturing organization.


The continued safe and reliable operation of equipment and efficient repairs is the responsibility of the maintenance engineer.


The management of a complex technical venture is different from normal business management. It requires knowledge of both engineering and of management techniques. Most engineering managers are promoted from the ranks of engineers. Often these engineers have advanced training in business administration.

Development of Engineering

The building of canals, bridges, and roads was carried out by specially trained civil engineers as early as the middle of the 18th century. With the advent of steam power at the beginning of the Industrial Revolution in the last part of the 18th century, mechanical engineers started to develop engines, locomotives, and various other machines. The automatic knitting machine was probably the most advanced technology. Originally steam was used merely to extend power beyond that of animals. During the 19th century, however, mechanical engineering expanded to include such labor-saving devices as the sewing machine and the mechanical reaper.

The increasing need for metals furthered mining engineering. With the invention of the Bessemer steel-making process, steel began to replace iron in both machinery and construction. Large bridges and skyscrapers became possible. This led to the development of metallurgical engineering as a separate field. The invention of electric generators and motors and the development of the electric lightbulb led to the growth of electrical engineering, which was originally a subspecialty of mechanical engineering. Advances in chemistry during the latter half of the 19th century demanded that small-scale laboratories be extended to large-scale production, opening the way for the chemical engineer. These various fields of engineering all had been established by 1900.

Following the introduction of the assembly line by Henry Ford in 1913, the demands of the growing automobile industry led to the specialty of automotive engineering. The rapid spurt of airplane development following World War I led to the new field of aeronautical engineering. The increasing need for petroleum products to provide fuels for transportation and heating fostered petroleum engineering. With the development of radio just after the turn of the 20th century, electronic engineering—a part of electrical engineering—was born. Today almost all modern communications techniques depend on the electronic engineer. With the invention of the transistor in 1948, new vistas in communications and computing were opened. Later the information revolution added computer engineering as a new specialty.

The advent of nuclear power was reflected in the field of nuclear engineering. Combinations of medicine and technology to build artificial limbs and organs and to improve medical instrumentation started the field of bioengineering. The need to produce goods cheaply and efficiently became a primary responsibility of the industrial engineer. Following the development of space flight, astronautical engineering was added to aeronautical engineering.

The invention of computers not only created a subspecialty in engineering but also changed the way all engineers work. Many structures, components, and processes are designed, modeled, and tested with the aid of computer programs. For example, they carry out all the technical computations needed to make a machine part meet performance requirements. This aspect of computer-aided design (CAD) is frequently coupled with computer-aided manufacture (CAM) to produce parts automatically. The use of robots is a major factor in the increasing automation of factories.

Engineering Education

Until the 18th century, engineering was essentially a craft in which cumulative experience was considered more important than formal learning. The exception was military engineering, in which formal education dates back to the middle of the 17th century. Education civil engineering began in 1747 with the founding in France of the National School of Bridges and Highways. France influenced the United States. The first American school of engineering was the United States Military Academy at West Point, N.Y., founded in 1802. Several two-year schools were founded before 1830 that emphasized technical education. Some of these eventually evolved into engineering colleges. The oldest are Norwich University in Vermont (1819) and the Rensselaer Institute of Technology in Troy, N.Y. (1824). American engineering education did not grow much, however, until after the Civil War, when state universities were founded with federal land grants to “teach agriculture and the mechanic arts.”

Such practical crafts courses as machine shop, surveying, drafting, and welding were offered in almost all schools. Although mathematics and the physical sciences were incorporated into engineering education early on, the development of scientifically based engineering courses began only after 1950.


Engineering is a challenging course of study that requires a thorough understanding of mathematics and science. These are normally taken in the first two years. Humanities and social studies also form a part of engineering programs. Such courses are included because engineers must consider the social effects of the products and processes they devise. Good oral and written communication skills also are needed. The last two years of the undergraduate curriculum are devoted almost entirely to technical courses.

More than 325 schools in the United States have one or more engineering programs accredited by the Accrediting Board for Engineering and Technology (ABET). There are also nonaccredited programs, but graduation from a nonaccredited program may make the student ineligible for a professional engineering license in some states or bar employment by federal agencies.

Accreditation in Canada is carried out by the Canadian Accrediting Board of the Canadian Council of Professional Engineers. Programs in more than 35 colleges and universities are accredited.

Many students begin their engineering careers right after graduation, while others go on to graduate study. Some undertake graduate work part-time while employed as engineers. Other graduates use their engineering education to enter a variety of fields, including business administration, medicine, and law.


With the continuing and rapid changes in technology, it is difficult to teach enough engineering in a four-year undergraduate curriculum. Both master’s and doctoral programs stress further technical depth. In the latter an independent research program resulting in a thesis is also required. Engineers planning to enter management frequently also undertake advanced study in business administration.

Continuing Education

Electrical engineers who graduated in the early 1950s would not know about transistors or computers unless they learned about them after leaving college. Engineers can become rapidly obsolete unless they recognize the need for lifelong learning in the profession through continuing education courses offered by universities, professional societies, and other groups. In some areas, continuing education credits are required in order to renew a professional engineering license.

Professional Societies

To remain current in their field, most engineers join one or more professional engineering societies. These societies publish technical journals, encourage engineering research, provide assistance to governments, hold meetings at which technical advances are presented, offer continuing education courses, and look after the technical welfare of their members.

One of the earliest civil engineering societies formed was the Institution of Civil Engineers (ICE), established in the United Kingdom in 1818. Some of the major U.S. societies date to the late 1800s: the American Society of Civil Engineers (ACSE) was founded in 1852; the American Institute of Mining, Metallurgical, and Petroleum Engineers (AIME) in 1871; the American Society of Mechanical Engineers (ASME) in 1880; the forerunner of the Institute of Electrical and Electronics Engineers (IEEE) in 1884. The organization that later became the Engineering Institute of Canada (EIC), now a federation of Canadian engineering societies, was established in 1887.

A myriad of professional societies for engineers in all specialties were founded in the 20th century, including the American Institute of Chemical Engineers (AIChE), the Institute of Industrial Engineers (IIE), the American Nuclear Society (ANS), the American Institute of Aeronautics and Astronautics (AIAA), and the Biomedical Engineering Society (BMES), in the United States; Engineers Australia; and the Institution of Engineers (IEI) in India. The World Federation of Engineering Organizations (WFEO) of the United Nations is an international umbrella organization of professional societies in the field.

Additional Reading

Billington, D.P. The Innovators (Wiley, 1996).Cadbury, Deborah. Dreams of Iron and Steel (Fourth Estate, 2004).Florman, Samuel. The Existential Pleasures of Engineering, 2nd ed. (St. Martin’s Griffin, 1996).Greene, Meg. Eiffel Tower (Blackbirch, 2004).Kemper, J.D., and Sanders, B.R. Engineers and Their Profession, 5th ed. (Oxford Univ. Press, 2001).Parkyn, Neil, ed. The Seventy Wonders of the Modern World (Thames & Hudson, 2002).Petroski, Henry. Invention by Design: How Engineers Get from Thought to Thing (Harvard Univ. Press, 1996).Rae, John, and Volti, Rudi. The Engineer in History, rev. ed. (Lang, 2001).