You see things; and you say "Why?" But I dream things that never were; and I say "Why not?" óGeorge 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. This is no contradiction.

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 to an engineering structure. 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.