The article discusses different theories about why unemployment happens. In the 1970s and 1980s, classical and Keynesian ideas were debated. A model called structuralist became popular in the 1990s, combining both classical and Keynesian views. This model looks at how changes in inflation relate to unemployment. It shows that policies to stabilize the economy are important for reducing unemployment. The article also talks about how globalization and new technology affect different types of jobs. It suggests that trade and biased technical change may not always lead to job losses for unskilled workers.