The document discusses gross domestic product (GDP) and how it is used to measure the overall health and output of an economy. GDP measures the total market value of all final goods and services produced within a country in a given period of time. It provides a measure of both production, or output, as well as income. When GDP increases, both national output and income are higher. GDP data can also be used to compare living standards across countries and measure economic growth over time by adjusting for inflation.