TOC systematically focus efforts, energy and attention on the "system constraint." This constraint, or bottleneck, restricts the output of the entire system and at the same time represents the primary leverage point for improving it. TOC adopts the common idiom "a chain is no stronger than its weakest link". This means that processes, organizations, etc., are vulnerable because the weakest process or part can always damage or break them or at least adversely affect the outcome.