UPSC is a constitutional authority under Article 315 of the constitution, that serves as the central recruiting agency for All India services, and group A & B posts of the Central services.
Jurisdiction of UPSC can be extended by the Parliament. The President can exclude posts, services and matters from the purview of the UPSC.
UPSC advises the government on recruitment related matters, but the advice is not binding on the government. It is also not consulted for highest diplomatic posts. UPSC is not concerned with the classification of services, pay and service conditions, cadre management, training, etc. These matters are handled by Department of Personnel and Training (DoPT). UPSC is just a central recruiting agency, DoPT is the central personnel agency.
Composition, appointment and removal of members:
UPSC consists of a chairman and other members appointed by the president of India. No qualifications are prescribed for the commission’s membership except that one-half of the members of the commission should be such persons who have held office for at least ten years under the government. Members can be removed by an order of the President, without requiring any sanction/resolution by the parliament. A Supreme Court inquiry is required when the removal is being made on grounds of misbehaviour.
Federal Public Service Commission, under Government of India Act 1935, was the predecessor organisation of UPSC.