Unemployment occurs when a person is available to work and currently seeking work, but the person is without work. The prevalence of unemployment is usually measured using the unemployment rate, which is defined as the percentage of those in the labor force who are unemployed. The unemployment rate is also used in economic studies and economic indexes such as the United States' Conference Board's Index of Leading Indicators as a measure of the state of the macroeconomics.
According to economist Edmond Malinvaud, the type of unemployment that occurs depends on the situation at the goods market, rather than that they belong to opposing economic theories. If the market for goods is a buyers' market (i.e.: sales are restricted by demand), Keynesian unemployment may ensue while a limiting production capacity is more consistent with classical unemployment.
A common typology of unemployment is the following
 Frictional unemployment
Frictional unemployment occurs when a worker moves from one job to another. While he searches for a job he is experiencing frictional unemployment. This applies for fresh graduates looking for employment as well. This is a productive part of the economy, increasing both the worker's long term welfare and economic efficiency. It is a result of imperfect information in the labour market, because if job seekers knew that they would be employed for a particular job vacancy, almost no time would be lost in getting a new job, eliminating this form of unemployment.
 Classical unemployment
Classical or real-wage unemployment occurs when real wages for a job are set above the market-clearing level. This is often ascribed to government intervention, as with the minimum wage, or labour unions. Some, such as Murray Rothbard, suggest that even social taboos can prevent wages from falling to the market clearing level.
 Structural unemployment
Structural unemployment is caused by a...