Unemployment. Unemployment occurs when people above a specified age are not in paid employment but are available for work. Artists have used various techniques to depict the hardships and struggles associated with joblessness. In realistic paintings, unemployment can be portrayed through images of breadlines, factories, or workers seeking employment. In more abstract works, unemployment can be symbolized through empty landscapes, desolate urban environments, or figures expressing despair or alienation. By visually representing the human cost of unemployment, artists have sought to raise awareness and inspire social change. Unemployment is measured by the unemployment rate, which is the number of people who are unemployed as a percentage of the labour force. Unemployment and the status of the economy can be influenced by a country through, for example, fiscal policy. Furthermore, the monetary authority of a country, such as the central bank, can influence the availability and cost for money through its monetary policy. In addition to theories of unemployment, a few categorisations of unemployment are used for more precisely modelling the effects of unemployment within the economic system. Some of the main types of unemployment include structural unemployment, frictional unemployment, cyclical unemployment, involuntary unemployment and classical unemployment. Structural unemployment focuses on foundational problems in the economy and inefficiencies inherent in labor markets, including a mismatch between the supply and demand of laborers with necessary skill sets. Structural arguments emphasize causes and solutions related to disruptive technologies and globalization. Discussions of frictional unemployment focus on voluntary decisions to work based on individuals' valuation of their own work and how that compares to current wage rates added to the time and effort required to find a job. Causes and solutions for frictional unemployment often address job entry threshold and wage rates. According to the UN's International Labour Organization, there were 172 million people worldwide without work in 2018. Because of the difficulty in measuring the unemployment rate by, for example, using surveys or through registered unemployed citizens, statistical figures such as the employment-to-population ratio might be more suitable for evaluating the status of the workforce and the economy if they were based on people who are registered, for example, as taxpayers. The state of being without any work yet looking for work is called unemployment. Economists distinguish between various overlapping types of and theories of unemployment, including cyclical or Keynesian unemployment, frictional unemployment, structural unemployment and classical unemployment definition. Some additional types of unemployment that are occasionally mentioned are seasonal unemployment, hardcore unemployment, and hidden unemployment.