Unemployment rate
The share of the labor force that has no job, is available to work, and has looked for work in the past four weeks.
BLS counts someone as unemployed if they have no job, have actively looked for work in the past four weeks, and are available for work. People on temporary layoff waiting to be recalled count as unemployed without searching. Source 1
The labor force is everyone employed plus everyone unemployed. The rate comes from the household survey. Source 1 Source 2