Headquarters of the World Health Organization in Geneva, Switzerland.<unk>  is the health of the populations in the worldwide context; it has been defined as "the area of study, research and practice that places a priority on improving health and achieving equity in health for all people worldwide". Problems that transcend national borders or have a<unk>  political and economic impact are often emphasized. Thus,<unk>  is about worldwide health improvement (including mental health), reduction of disparities, and protection against<unk>  threats that disregard national borders.<unk>  is not to be confused with international health, which is defined as the branch of public health focusing on developing nations and foreign aid efforts by industrialized countries.<unk>  can be measured as a function of various<unk>  diseases and their prevalence in the world and threat to decrease life expectancy in the present day. Estimates suggest that in a pre-modern, poor world, life expectancy was around 30 years in all regions of the world. The predominant agency associated with<unk>  (and international health) is the World Health Organization (WHO). Other important agencies impacting<unk>  include UNICEF and World Food Programme (WFP). The United Nations system has also played a part with cross-sectoral actions to address<unk>  and its underlying socioeconomic determinants with the declaration of the Millennium Development Goals and the more recent Sustainable Development Goals. There are a number of major institutions of higher education that offer<unk>  as an area of study such as Harvard University, McGill University, The University of Western Ontario, Johns Hopkins University, University of Oxford, University of California, San Francisco, Columbia University, University of Washington, Duke University, University of Warwick, University of Bonn, Karolinska Institutet and the Balsillie School of International Affairs.
Global health
International health
Public health
Regulatory science
Environmental health
Community health
Social 
Pre-health sciences