The
Encyclopedia Britannica defines this as the application of
scientific methods to the the
management and
administration of organized military, governmental, commercial, and industrial
processes. Another way put, it is the use and development of
quantitative techniques to make decisions and solve problems. Areas that this discipline covers includes
resource allocation,
linear programming,
inventory control,
queuing,
network routing, and
search theory.
Originally developed during World War II to aid and refine processes, mostly in resource management and search theory. After the war the usage of such techniques found their way into many other more civilian applications. Such as finding a missing person or scheduling resources (this includes both people and hardware) on a task. Since this time it has influenced many other fields such as manufacturing, project management, artificial intelligence, software development, and others.
Search has greatly affected programming and specifically artificial intelligence. Much of AI can be thought of as programming Operations Research algorithms/techniques to relieve humans from mundane tasks. In fact the definition of OR about using quantitative techniques to solve problems is contained in one definition of AI. You just need to tack on "using an artificial agent" and it becomes what many define as the definition of AI.
Also known as Operational Research.