Everything depenos on everything else. This means that every economic activity has important backward and forward linkages with every other activity. Consequently, if output of one activity increases due to demand increases, it requires all its inputs also to be made available through production and/or imports. In the next stage, inputs of the domestically produced inputs also will have to be made available, and so on and on. Any bottlenecks in the supply of all these chain of inputs may create serious production bottlenecks. The possibility of any such structural imbalances in which shortages in certain sectors and surpluses in certain other group of sectors can occur, provide the most persuasive arguments for the study of structural interdependence using input output techniques.