It is one of the most important indicators of the level of economic activity and the size of the economy in a country. It expresses the total financial value of all goods and services produced locally during a certain period of time (a fiscal year). It is expressed mostly by the percentage of increase or decrease from the previous year.

Economists measure GDP in one of three ways that ultimately lead to the same value. First, by calculating the total public spending, which is equivalent to the sum of consumption, investment, government spending and net exports, secondly by calculating the total domestic production by adding the added values ​​of the goods and services that were sold locally, and third by calculating the total domestic income, which is equivalent to the total salaries, profits and taxes minus the government support values .

The World Bank issues an annual report on the classification of the economies of the world’s countries based on the value of gross domestic production. The report includes 214 economies worldwide. At the top of this ranking (for the year 2014) comes the United States of America, with a value of approximately 17.5 trillion US dollars, followed by China, Japan, Germany and then England in the list. The Kingdom of Saudi Arabia comes at the forefront of the Arab countries with a value of 746 billion US dollars in the nineteenth place, followed by the United Arab Emirates, Egypt, Iraq and Algeria.