Theory of Constraints (TOC) is a systemic approach to improvement that identifies inaccurate underlying assumptions and implements simple solutions. Some common inaccurate assumptions include that everyone must always be busy, buying in bulk is cheaper, and estimates are imprecise. These assumptions lead to behaviors like overproduction, excess inventory, delayed projects, and addressing conflicts through negative means. TOC seeks to identify the underlying conflicting constraint, implement a simple solution to break the conflict, and change rules to conform to the new environment created by the solution.