Gross Domestic Product (GDP)
GDP represents the market value of all final goods and services produced within a country during a given period. The figure is usually given in nominal and real formats, with real GDP adjusting for changes in monetary value. Given its vast breadth, this indicator is among the most watched by the financial markets.
The expansion of a country's GDP is indicative of a growing economy, while a contraction in GDP indicates a slowdown in a country's economy. Meanwhile, a country's projected GDP growth rate can be used to determine an appropriate level of sovereign debt or determine if companies operating within the country are likely to experience growth.
Consumer Price Index (CPI) and inflation
CPI measures changes in the prices of consumer goods and services that are purchased by households. The index is a statistical estimate created by using prices from a sample of representative items collected periodically. Often this measure is used as a gauge of inflation, which can positively or negatively affect a country's currency.
The financial markets carefully watch the CPI figures for signs of inflation. Rising inflation can lead to higher interest rates and reduced lending, while deflation can lead to lower interest rates and greater lending.
Inflation measured by the Consumer Price Index is defined as the change in the prices of a basket of goods and services that are typically purchased by specific groups of households. Inflation measures the erosion of living standards.
Ease of doing business index
The ease of doing business index is an index created by Simeon Djankov at the World Bank Group. Higher rankings (a low numerical value) indicate better, usually simpler, regulations for businesses and stronger protections of property rights. You can read how the index is built on Wikipedia.