During the COVID‐19 pandemic, key workers left the safety of their homes to produce, distribute and sell food, clean to minimize the spread of the pandemic, ensure public safety, transport essential goods and workers to their jobs, and care for and heal the sick. The pandemic made evident the extent to which societies need key workers – in both good times and bad – but also how undervalued most key jobs are, raising concerns about the sustainability of these essential activities. This chapters introduces the concept of key workers and provides basic demographic information on their composition.