Bureaucracy is a portion of a governance system designed to be neutral and insulated from political pressures. Bureaucracies tend to function on the basis of professionalism and meritocracy, rather than popular preference. They can counterbalance more transient political formations, such as elected officials and referendums.
Input: Externally defined priorities, meritocratic internal incentive structures, continuity through political change
Output: consistency of service delivery, neutral expertise in the service of popular priorities
Perhaps the most famous ancient bureaucracy was that developed in China's Han dynasty (202 BCE - 220 AD), which used expertise in Confucian philosophy as the basis for securing government positions. Other ancient governments developed bureaucratic structures as well.
Bureaucracy became a central feature of modern governments and corporations, providing operational continuity alongside policy changes from elected leaders.