The secondary sector is characterised by short-term employment relationships, little or no prospect of internal promotion, and the determination of wages primarily by market forces. In terms of occupations, it consists primarily of low or unskilled jobs, whether they are blue-collar (manual-labour), white-collar (e.g., filing clerks), or service jobs (e.g., waiters). These jobs are linked by the fact that they are characterized by "low skill levels, low earnings, easy entry, job impermanence, and low returns to education or experience." In a number of service jobs, such as food service, golf caddying, and valet parking jobs, workers in some countries are paid mostly or entirely with tips.
