The central constitutional body that conducts examinations and advises on recruitment to the All-India Services and the Central Services, including the CAPF (Assistant Commandants) exam.
The UPSC conducts the CAPF AC examination itself, and Articles 315 to 323 (especially 315, 320, 317) are core constitutional-body facts.
The UPSC (Union, Art 315) is distinct from the State Public Service Commissions; its advice is advisory, not binding; do not confuse it with the Staff Selection Commission (a non-constitutional body).
Art 315 constitutional recruitment body for central and all-India services (it runs the CAPF exam); advisory role, members protected under Art 317.