Policy is defined as a plan of collective action. Governments can influence the food systems through regulations, incentives or knowledge creation and dissemination. Government interventions may be needed to correct market failures, including the production of public good and compensation for externalities. Priorities for food systems vary over time and across countries but would usually include the improvement of the well-being of societies or specific stakeholder groups such as the poor and malnourished, producers or consumers. Most governments are likely to place their legitimacy over other goals.