Unemployment can be categorized as either natural (frictional and structural) or cyclical. Natural unemployment refers to unemployment that persists even during economic booms, such as time spent searching for a job (frictional) or skills that do not match available jobs (structural). Cyclical unemployment rises and falls with the business cycle. The Bureau of Labor Statistics measures unemployment monthly through surveys. While an imperfect measure, it provides useful information about joblessness over time. Most spells of unemployment are short term, but long-term unemployment accounts for most joblessness at any point. Government policies like employment agencies, training programs, and unemployment insurance can impact unemployment rates.