This document provides an overview of operational research. It defines operational research as applying scientific methods to optimize systems. The key approaches include orientation, problem definition, data collection, model formulation, model solution, validation, and implementation. Common techniques are linear programming, dynamic programming, queueing theory, inventory control, decision theory, network analysis, and simulation. These have been used across industries, defense, planning, agriculture, and public utilities. Overall, operational research is a tool that can improve productivity by optimizing systems through scientific problem solving.