Five Focusing Steps of Theory of Constraints

Evaporating clouds 

This is a term used to describe a methodology developed by Goldratt to resolve conflicts in a 'win-win' manner. The name relates to the idea that conflicts, like clouds, are often indistinct (ie, people are unable to articulate the real reasons for the conflict). The 'evaporating' part refers to the tool's ability to dissipate the confusion surrounding the conflict, clearly identify the key elements, and provide a means for resolving the conflict. 

Reality trees 

A reality tree is a cause-and-effect tree (current or future), construction of which is governed by rigorous rules of logic (eight of them). It starts with 'roots' in a cause of some kind, develops upward through a 'trunk' and 'branches' of several layers of intermediate effects, to the 'leaves', which are the ultimate effects. 

Drum-buffer-rope principle 

Consider a manufacturing company, it's easier! - The idea here is that the constraint (usually a machine) is the drum which beats at a certain rate (material throughput) while the buffer (of stock) protects the constraint from running out of material to process and the rope connects the rate of throughput to the incoming material supply. 

Goldratt advises that any constraint having been identified is only transitional. As this constraint is exploited, another will appear in its place. Without identifying constraints, Goldratt suggests that management may not be able to identify constraints but take actions to work around the problem. 

TOC based performance measurement means that new measures of performance will be needed as constraints are identified and measures devised to specifically measure their performance in relation to goal achievement.