A temporary agency may be distinct from a recruitment firm, which seeks to place permanent employees, but there is often a large overlap: temporary workers may go on to become permanent employees; or workers a company intends to hire as a permanent employee may start out as trial temporary worker.

In the UK the temporary worker is technically employed by the recruitment agency whilst working on site for the client who pay the bills. The agency is responsible for paying the temporary worker plus paying employers national insurance to the government and setting aside holiday pay (working time directive or WTR (regulations)). This total cost then has a profit margin added and is charged per hour to the client. The temporary worker fills in timesheets (often online) and is paid by BACS on a weekly basis. Some industries in the UK are more heavily regulated by the gangmaster regulations.

Many temporary agencies specialize in a particular profession or field of business, such as accounting, health care, technical, or secretarial.