Engineering is the application of scientific and technical knowledge to solve human problems. Engineers use imagination, judgment and reasoning to apply science, technology, mathematics, and practical experience. The result is the design, production, and operation of useful objects or processes.

Methodology

The crucial and unique task of the engineer is to identify, understand, and integrate the constraints on a design in order to produce a successful result. It is usually not enough to build a technically successful product; it must also meet further requirements. Constraints may include available resources, physical or technical limitations, flexibility for future modifications and additions, and other factors, such as requirements for cost, marketability, producibility, and serviceability. By understanding the constraints, engineers derive specifications for the limits within which a viable object or system may be produced and operated.
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Problem solving

Engineers use their knowledge of science, mathematics, and appropriate experience to find suitable solutions to a problem. Creating an appropriate mathematical model of a problem allows them to analyze it (sometimes definitively), and to test potential solutions. Usually multiple reasonable solutions exist, so engineers must evaluate the different design choices on their merits and choose the solution that best meets their requirements. Genrich Altshuller, after gathering statistics on a large number of patents, suggested that compromises are at the heart of "low-level" engineering designs, while at a higher level the best design is one which eliminates the core contradiction causing the problem.

Engineers typically attempt to predict how well their designs will perform to their specifications prior to full-scale production. They use, among other things: prototypes, scale models, simulations, destructive tests, nondestructive tests, and stress tests. Testing ensures that products will perform as expected. Engineers as professionals take seriously their responsibility to produce designs that will perform as expected and will not cause unintended harm to the public at large. Engineers typically include a factor of safety in their designs to reduce the risk of unexpected failure. However, the greater the safety factor, the less efficient the design may be.


Computer use

As with all modern scientific and technological endeavours, computers and software play an increasingly important role. Numerical methods and simulations can help predict design performance more accurately than previous approximations.

Using computer-aided design (CAD) software, engineers are able to more easily create drawings and models of their designs. Computer models of designs can be checked for flaws without having to make expensive and time-consuming prototypes. The computer can automatically translate some models to instructions suitable for automatic machinery (e.g., CNC) to fabricate (part of) a design. The computer also allows increased reuse of previously developed designs, by presenting an engineer with a library of predefined parts ready to be used in designs. Computers can also be used as part of the manufacturing process, controlling the machines and ensuring a constant level of quality and similarity in the products. This process is Computer Aided Manufacture (CAM) and works in a similar way to CNC but where CNC controls the machinery, CAM controls the whole manufacture process from cutting to assembly.

Of late, the use of finite element method analysis (FEM analysis or FEA) software to study stress, temperature, flow as well as electromagnetic fields has gained importance. In addition, a variety of software is available to analyse dynamic systems.

Electronics engineers make use of a variety of circuit schematics software to aid in the creation of circuit designs that perform an electronic task when used for a printed circuit board (PCB) or a computer chip.

The application of computers in the area of engineering of goods is known as Product Lifecycle Management (PLM).
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Etymology

The Oxford English Dictionary gives one, now obsolete, meaning of engineer (dating from 1325) as "A constructor of military engines". Engineering was originally divided into military engineering (which included construction of fortifications as well as military engines) and civil engineering (non-military construction of such as bridges).

The words engine and engineer (as well as ingenious) developed in parallel from the Latin root ingeniosus, meaning "skilled". An engineer is thus implied to be a clever, practical, problem solver.

With the rise of engineering as a profession in the nineteenth century the term became more narrowly applied to fields in which mathematics and science were applied to these ends. In some other languages, such as Arabic, the word for "engineering" also means "geometry".

In the nineteenth century in addition to military and civil engineering the fields then known as the mechanic arts became incorporated into engineering.


Engineering in a social context

Engineering is a subject that ranges from large collaborations to small individual projects. Almost all engineering projects are beholden to some sort of financing agency: a company, a set of investors, or a government. The result of this is that large-scale engineering projects often lose much of their original purpose to some form of bureaucracy. The few types of engineering that are minimally constrained by such issues are pro bono engineering and open design engineering.
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Cultural presence

Engineering is a well respected profession. For example, in Canada it ranks as one of the public's most trusted professions [1].

Sometimes engineering has been seen as a somewhat dry, uninteresting field in popular culture, and has also been thought to be the domain of nerds. For example, the cartoon character Dilbert is an engineer.

This has not always been so - most British school children in the 1950s were brought up with stirring tales of 'the Victorian Engineers', chief amongst whom where the Brunels, the Stephensons, Telford and their contemporaries.

In science fiction engineers are often portrayed as highly knowledgeable and respectable individuals who understand the overwhelming future technologies often portrayed in the genre. The Star Trek characters Montgomery Scott and Geordi La Forge are famous examples.

Engineers are often respected and ridiculed for their intense beliefs and interests. Perhaps because of their deep understanding of the interconnectedness of many things, engineers such as Governor John H. Sununu, New York City Mayor Michael Bloomberg and Nuclear Physicist Edward Teller, are often driven into politics to "fix things" for the public good.

Occasionally, engineers may be recognized by the "Iron Ring"--a stainless steel or iron ring worn on the little (fourth) finger of the dominant hand. This tradition was originally developed in Canada in the Ritual of the Calling of an Engineer as a symbol of pride and obligation for the engineering profession. Some years later this practice was adopted in the United States. Members of the US Order of the Engineer accept this ring as a pledge to uphold the proud history of engineering. A Professional Engineer's name often has the post-nominal letters PE or P.Eng.

While it appears Engineers still only need a bachelor's degree to obtain a lucrative position that receives respect from the public, in fact it is only through a life-time devotion to their field and the further advancement of their own technical knowledge that they might arrive at such a destination.


Legislation

In most modern countries, certain engineering tasks, such as the design of bridges, electric power plants, and chemical plants, must be approved by a Professional Engineer or a Chartered Engineer.

Laws protecting public health and safety mandate that a professional must provide guidance gained through education and experience. In the United States, each state tests and licenses Professional Engineers.

The federal government, however, supervises aviation through the Federal Aviation Regulations administrated by the Dept. of Transportation, Federal Aviation Administration. Designated Engineering Representatives approve data for aircraft design and repairs on behalf of the Federal Aviation Administration.

Even with strict testing and licensure, engineering disasters still occur. Therefore, the Professional Engineer or Chartered Engineer adheres to a strict code of ethics. Each engineering discipline and professional society maintains a code of ethics, which the members pledge to uphold.

In Canada the profession in each province is governed by its own engineering association. For instance, in the Province of British Columbia an engineering graduate with 5 or more years of experience in an engineering-related field will need to be certified by the Association for Professional Engineers and Geoscientists (APEGBC) in order to become a Professional Engineer.

Refer also to the Washington accord for international accreditation details of professional engineering degrees.

Comparison to other disciplines


Science

You see things; and you say "Why?" But I dream things that never were; and I say "Why not?" —George Bernard Shaw

Engineering is concerned with the design of a solution to a practical problem. A scientist may ask why a problem arises, and proceed to research the answer to the question or actually solve the problem in his first try, perhaps creating a mathematical model of his observations. By contrast, engineers want to know how to solve a problem, and how to implement that solution. In other words, scientists attempt to explain phenomena, whereas engineers use any available knowledge, including that produced by science, to construct solutions to problems.

There is an overlap between science (fundamental and applied) and engineering. It is not uncommon for scientists to become involved in the practical application of their discoveries; thereby becoming, for the moment, engineers. Scientists may also have to complete engineering tasks, such as designing experimental apparatus or building prototypes. Conversely, in the process of developing technology engineers sometimes find themselves exploring new phenomena, thus becoming, for the moment, scientists.

However, engineering research has a character different from that of scientific research. First, it often deals with areas in which the basic physics and/or chemistry are well understood, but the problems themselves are too complex to solve in an exact manner. The purpose of engineering research is then to find approximations to the problem that can be solved. Examples are the use of numerical approximations to the Navier-Stokes equations to solve aerodynamic flow over an aircraft, or the use of Miner's rule to calculate fatigue damage . Second, engineering research employs many semi-empirical methods that are foreign to pure scientific research, one example being the method of parameter variation.

In general, it can be stated that a scientist builds in order to learn, but an engineer learns in order to build.