Operations research is also known as "management science." In short, this field is concerned with using mathematics to solve problems and make optimal decisions in situations where resources are limited. This is a wide field with many methods and models, all arriving from the need to solve a particular problem.
The primary methods of operations research almost all stem from linear programming. Linear programming is one of the most powerful and common methods of operations research. The basic notion of linear programming is how to optimize a mathematical function (find its maximum or minimum value) when the variables involved in the equation are under linear restraints. Most other methods in operations research are advanced or modified versions of linear programming. Some examples are nonlinear programming, multiobjective programming and integer programming.
Operations research makes heavy use of mathematical modeling. Two of the more common modeling techniques in operations research are network models and location models. Network models are derived from graph theory and use pictures to describe possible decision-making paths. Network models can be applied to many areas in operations research, such as the planning of online network flow, logistical decision making and city planning. Another common model type is the location model. The location model uses customers, facilities and space as variables to solve problems related to competition of businesses, supply and demand and other location-related decision-making issues.
Operations research, being a large field, encompasses and makes use of too many methods and models to conveniently list. Depending on the application, operations research may employ methods that are rigorously mathematical or visually informative. Project networks, machine scheduling, decision analysis, inventory models, random processes, queue models and simulation models all play important roles in operations research. While each model and method is focused on solving one type of problem, they all are oriented toward an overall goal: helping the user make the best decision.