In the absence of an internationally recognised definition of complementarity, the Commission defines it as the optimal division of labour between various actors in order to achieve optimum use of human and financial resources.

Globalisation increases the international division of labour as transportation and communication costs have substantially decreased.

[4] CEPII (2004), European industry's place in the International Division of Labour: situation and prospects.

If the phenomenon of market opening of industrialised economies is not a new one, the actors and the modalities of this international division of labour have changed: a rapid development since the first oil crisis, the end of the traditional international division of labour between North and South, a new competition from the countries of the South without the dominant position of the North in World trade being seriously undermined, a division of labour within branches and not only between branches, an international segmentation of production processes.

Some regard import dependence as a normal consequence of the international division of labour and globalisation, and consider that dependence risks are reduced by mutual trade and investment and by good relations between producers and consumers.

While border regions may be affected more quickly and more intensively by enlargement than other regions, their proximity to candidate countries will offer new possibilities, for example through increased division of labour with candidate countries.