American unemployment rates utilize five measures in addition to the headline H3 figures: U-1, U-2, U-4, U-5, and U-6. Each of these incrementally considers additional groups of individuals and labels them as unemployed (e.g., those "underemployed" or working part-time but seeking full employment, etc.) The U-6 number is sometimes referred to as the "real" unemployment rate since it is the most comprehensive.