irregular employment or part-time labour, including the labour of workers whose normal employment consists of a series of short-term jobs. Casual labour is usually hired by the hour or day or for the performance of specific tasks, while part-time labour is typically scheduled for a minimum number of hours per week.

A typical casual labourer of the late 19th and early 20th centuries was the dock worker. Other major industries that have relied heavily on casual labour are construction, logging, sawmilling, agriculture, and the service trades.

Part-time labour is often preferred by students and retirees who seek regular scheduled work but are not able to work on a full-time basis. Part-time workers can be less costly to employ. For example, businesses in the United States are not required to provide part-time employees with health insurance or other benefits. The use of casual and part-time labour allows employers greater flexibility in hiring and firing and thus enables them to adjust to swings in production.