World economy

The world economy or global economy is the economy of the world, considered as the international exchange of goods and services that is expressed in monetary units of account (money). In some contexts, the two terms are distinguished: the "international" or "global economy" being measured separately and distinguished from national economies while the "world economy" is simply an aggregate of the separate countries' measurements. Beyond the minimum standard concerning value in production, use, and exchange the definitions, representations, models, and valuations of the world economy vary widely. It is inseparable from the geography and ecology of Earth.

It is common to limit questions of the world economy exclusively to human economic activity, and the world economy is typically judged in monetary terms, even in cases in which there is no efficient market to help valuate certain goods or services, or in cases in which a lack of independent research or government cooperation makes establishing figures difficult. Typical examples are illegal drugs and other black market goods, which by any standard are a part of the world economy, but for which there is by definition no legal market of any kind.

However, even in cases in which there is a clear and efficient market to establish a monetary value, economists do not typically use the current or official exchange rate to translate the monetary units of this market into a single unit for the world economy, since exchange rates typically do not closely reflect worldwide value, for example in cases where the volume or price of transactions is closely regulated by the government.

Rather, market valuations in a local currency are typically translated to a single monetary unit using the idea of purchasing power. This is the method used below, which is used for estimating worldwide economic activity in terms of real US dollars or euros. However, the world economy can be evaluated and expressed in many more ways. It is unclear, for example, how many of the world's 7.13 billion people have most of their economic activity reflected in these valuations.

As of 2015, the following 13 countries or regions have reached an economy of at least US$2 trillion by GDP in nominal or PPP terms: Brazil, China, France, Germany, India, Indonesia, Italy, Japan, Mexico, Russia, United Kingdom, United States, and European Union.

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