Industrialisation (UK) or industrialization (US) is the period of social and economic change that transforms a human group from an agrarian society into an industrial society. This involves an extensive reorganisation of an economy for the purpose of manufacturing. Industrialisation is associated with increase of polluting industries heavily dependent on fossil fuels. With the increasing focus on sustainable development and green industrial policy practices, industrialisation increasingly includes technological leapfrogging, with direct investment in more advanced, cleaner technologies.