Trade liberalization and the emergence of a global economy have permitted the purchasing offices of the world's businesses to systematically comb the world's markets for the best and least expensive products, components and raw materials. This practise may be referred to as "global sourcing". With purchased materials typically the largest category of cost in many products, it is impossible to gain and sustain a competitive advantage without a vigorous sourcing programme. Firms more interested in global sourcing tend to be those whose manufacturing processes heavily rely on simple parts (or raw materials). The Automotive and aerospace industries are, therefore, prime movers in the field.