Being unemployed means you don’t have a job but you are looking for a job and could take a job if only one were offered. In other words, if you don’t want to work and you are not working, you are not unemployed. The US government closely tracks the unemployment rate because most economists consider the data to be among the best indicators of overall economic health.
Aside from the crushing individual losses caused by unemployment, there is a national cost associated with high unemployment. After all, if tens of thousands of Americans aren’t working they aren’t producing anything, they aren’t cashing paychecks, and they aren’t fueling the economy with their labor.