Define unemployment and how it is expressed in most countries.

Percentage of total workforce who are unemployed and are actively seeking a paid job.
Unemployment rate (# of unemployed / # in labor force) = %
Unemployment rate is one of the most closely watched statistics because a rising rate is seen as a sign of weakening economy that may call for cut in interest rate. A falling rate, similarly, indicates a growing economy which is usually accompanied by higher inflation rate and may call for increase in interest rates.