International development or global development is a broad concept denoting the idea that societies and countries have differing levels of economic or human development on an international scale. It is the basis for international classifications such as developed country, developing country and least developed country, and for a field of practice and research that in various ways engages with international development processes. There are, however, many schools of thought and conventions regarding which are the exact features constituting the "development" of a country. Historically, development was largely synonymous with economic development, and especially its convenient but flawed quantification (see parable of the broken window) through readily gathered (for developed countries) or estimated monetary proxies (estimated for severely undeveloped or isolationist countries) such as gross domestic product (GDP), often viewed alongside actuarial measures such as life expectancy. More recently, writers and practitioners have begun to discuss development in the more holistic and multi-disciplinary sense of human development. Other related concepts are, for instance, competitiveness, quality of life or subjective well-being. "International development" is different from the simple concept of "development". Whereas the latter, at its most basic, denotes simply the idea of change through time, international development has come to refer to a distinct field of practice, industry, and research; the subject of university courses and professional categorisations. It remains closely related to the set of institutions—especially the Bretton Woods Institutions—that arose after the Second World War with a focus on economic growth, alleviating poverty, and improving living conditions in previously colonised countries. The international community has codified development aims in, for instance, the Millennium Development Goals (2000 to 2015) and the Sustainable Development Goals (2015 to 2030).