The unemployment rate is the number of unemployed workers divided by the total civilian labour force, which includes both the unemployed and those with jobs (all those willing and able to work for pay). In practice, measuring the number of unemployed workers actually seeking work is notoriously difficult. There are several different methods for measuring the number of unemployed workers. Each method has its own biases and the different systems make comparing unemployment statistics between countries, especially those with different systems, difficult.

The graph shows the official unemployment rate (as a percentage of the labour force) in the United States from 1948 to the present (using data supplied by the Bureau of Labor Statistics). The terms unemployment and unemployed are sometimes used to refer to other inputs to production that are not being fully used -- for example, unemployed capital goods.

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