Theory of constraints (TOC) is about thinking in logical and systematic way similar to the Plan do check act (PDCA) learning loop. It is not only about analyzing the causes and effect but also verifying basic assumptions, exploring alternatives and process improvement. The goal of TOC is to maximize the efficiency, profitability, quality of work. This paper includes basic theoretical information about TOC. It basically helps in problem solving & implementing the solution for the same. TOC is majorly applied in manufacturing sector, including distribution, marketing, project management, and accounting. In short, any situation involving change to a system TOC is applied