The concept of Constraints refers to all the performance-limiting factors within a flow, be they physical, financial or information flow.
A constraint is therefore an obstacle which slows down the whole system’s progress toward its goal, but any system must by definition be subject to at least one constraint, without which every initiative would be successful and performance would be limitless (The Goal, by Eliyahu Goldratt).
Constraints and bottleneck #
Constraints are often mistaken with bottlenecks, which are in fact not necessarily a constraint. While the constraint can be located in the weakest link of a production flow, in which case it coincides with the bottleneck, but it can just as easily be located in any other section of the system, not necessarily the weakest area.