Quality Systems
A quality management system is the documented structure of processes, responsibilities, and records that gives an organization confidence requirements will be met consistently. ISO 9001:2015 is organized around context of the organization, leadership, planning, support, operation, performance evaluation, and improvement, and rests on seven principles: customer focus, leadership, engagement of people, process approach, improvement, evidence-based decision making, and relationship management. Two ideas drive modern questions: the process approach (inputs, outputs, controls, and risks per process rather than per department) and risk-based thinking - the 2015 revision dropped the discrete preventive action clause and folded prevention into risk identification and planning.
Know the document hierarchy: quality policy and objectives, quality manual (no longer mandatory but still common), procedures and work instructions, and records. Documents are controlled - approved, versioned, retrievable; records are retained evidence and are never revised. Corrective action eliminates the cause of a detected nonconformity; correction fixes the instance; preventive action addresses a potential nonconformity.
Audits: first-party (internal), second-party (supplier or customer), third-party (certification body). Certification bodies certify organizations; accreditation bodies (e.g., ANAB, UKAS) accredit certifiers and laboratories. Sector schemes: AS9100 (aerospace), IATF 16949 (automotive), ISO 13485 (medical devices), ISO/IEC 17025 (testing and calibration labs), ISO 14001 (environmental).
Worked example. An internal audit finds an unapproved procedure revision in use. Correction: withdraw it and use the approved revision. Corrective action: investigate why document control failed, fix distribution and training, then verify effectiveness at the next audit.