This refers to a graphical representation that shows the relationship between the unemployment rate (on the horizontal axis) and the job vacancy rate (on the vertical axis) in an economy. It is named after British economist William Beveridge. The Beveridge curve usually slopes downwards because times when there is high job vacancy in an economy are also marked by relatively low unemployment since companies may actually be actively looking to hire new people. By the same logic, a low job vacancy rate usually corresponds with high unemployment as companies may not be looking to hire many people in new jobs.
