GDP and GNI

GDP is the value of all final output of goods and services in a given economy in a given year. Nominal GDP measures this using current prices of all goods and services. This means inflation is not taken into account. 

Real GDP measures all final output of goods and services in a given economy in a given year, but uses constant prices, which adjusts for inflation. This calculation is done by using a price deflator. Using the deflator value, you can calculate real GDP

Real GDP = Nominal GDP / Price Deflator

GDP Per Capita is a country's GDP divided by the number of people in the country. This is useful to see how productive an average person is in that economy. 

Real GDP Per Capita = Real GDP / Population

Purchasing power parity refers to how many goods and services the GDP will actually get you. This is a useful indicator as it shows what the economy's size actually means.

Example: Even though 1 US Dollar gives you 80 Indian Rupees, you can buy a lot more things for 80 Rupee in India than 1 Dollar in the US, because goods and services are generally cheaper in India. India's Real GDP Per Capita adjusted for PPP is therefore a higher value than its regular Real GDP Per Capita, compared to the US which probably has a lower value.

GNI is GDP, plus a net factor income from abroad. That is, it includes money earned by your citizens/firms abroad, but minus money earned by foreign workers/firms in your country.

Another way to think about this is that GNI counts all income generated by a country's citizens and companies, no matter in what country they are.

Example: If Toyota owns a factory in the US, the production of cars counts towards the US' GDP, but the profit made on the factory counts towards Japan's GNI. This profit is subtracted from the US's GNI.

GNI = GDP + Net incomes abroad

Real GNI is the GNI-value adjusted for inflation, which is done using a price deflator, just like real GDP.

The same principle as Real GDP/Capita; Useful to see productivity.

The same principle as Real GDP/Capita at PPP; Useful to see what the economy's size can actually do