Quality control (QC) is a process by which entities review the quality of all factors involved in production. ISO 9000 defines quality control as "A part of quality management focused on fulfilling quality requirements". 
- Elements such as controls, job management, defined and well managed processes,   performance and integrity criteria, and identification of records
- Competence, such as knowledge, skills, experience, and qualifications
- Soft elements, such as personnel, integrity, confidence, organizational culture, motivation, team spirit, and quality relationships.
Inspection is a major component of quality control, where physical product is examined visually (or the end results of a service are analyzed). Product inspectors will be provided with lists and descriptions of unacceptable product defects such as cracks or surface blemishes for example. 
Early stone tools such as anvils had no holes and were not designed as interchangeable parts. Mass production established processes for the creation of parts and system with identical dimensions and design, but these processes are not uniform and hence some customers were unsatisfied with the result. Quality control separates the act of testing products to uncover defects from the decision to allow or deny product release, which may be determined by fiscal constraints.  For contract work, particularly work awarded by government agencies, quality control issues are among the top reasons for not renewing a contract. 
The simplest form of quality control was a sketch of the desired item. If the sketch did not match the item, it was rejected, in a simple Go/no go procedure. However, manufacturers soon found it was difficult and costly to make parts be exactly like their depiction; hence around 1840 tolerance limits were introduced, wherein a design would function if its parts were measured to be within the limits. Quality was thus precisely defined using devices such as plug gauges and ring gauges. However, this did not address the problem of defective items; recycling or disposing of the waste adds to the cost of production, as does trying to reduce the defect rate. Various methods have been proposed to prioritize quality control issues and determine whether to leave them unaddressed or use quality assurance techniques to improve and stabilize production. 
There is a tendency for individual consultants and organizations to name their own unique approaches to quality control—a few of these have ended up in widespread use:
|Terminology||Approximate year of first use||Description|
|Statistical quality control (SQC)||1930s||The application of statistical methods (specifically control charts and acceptance sampling) to quality control : 556|
|Total quality control (TQC)||1956||Popularized by Armand V. Feigenbaum in a Harvard Business Review article  and book of the same name;  stresses involvement of departments in addition to production (e.g., accounting, design, finance, human resources, marketing, purchasing, sales)|
|Statistical process control (SPC)||1960s||The use of control charts to monitor an individual industrial process and feed back performance to the operators responsible for that process; inspired by control systems|
|Company-wide quality control (CWQC)||1968||Japanese-style total quality control. |
|Total quality management (TQM)||1985||Quality movement originating in the United States Department of Defense that uses (in part) the techniques of statistical quality control to drive continuous organizational improvement |
|Six Sigma (6σ)||1986||Statistical quality control applied to business strategy;  originated by Motorola|
|Lean Six Sigma (L6σ)||2001||Six Sigma applied with the principles of lean manufacturing and/or lean enterprise; originated by Wheat et al. |
In project management, quality control requires the project manager and/or the project team to inspect the accomplished work to ensure its alignment with the project scope.  In practice, projects typically have a dedicated quality control team which focuses on this area. 
- Analytical quality control
- Corrective and preventative action (CAPA)
- Eight dimensions of quality
- First article inspection (FAI)
- Good Automated Manufacturing Practice (GAMP)
- Good manufacturing practice
- Quality assurance
- Quality management framework
- Standard operating procedure (SOP)
- ISO 9000:2005, Clause 3.2.10
- Praxiom Research Group Limited (16 August 2017). "ISO 9001 Translated Into Plain English". Praxiom Research Group Limited. Retrieved 29 November 2017.
- Aft, L.S. (1997). "Chapter 1: Introduction". Fundamentals of Industrial Quality Control. CRC Press. pp. 1–17.
- Dennis Adsit (9 November 2007). "What the Call Center Industry Can Learn from Manufacturing: Part I" (PDF). National Association of Call Centers. Retrieved 21 December 2012.
- Dennis Adsit (23 November 2007). "What the Call Center Industry Can Learn from Manufacturing: Part II" (PDF). National Association of Call Centers. Retrieved 21 December 2012.
- Shewhart, Walter A. (Walter Andrew); Deming, W. Edwards (William Edwards) (1939). Statistical method from the viewpoint of quality control. Washington: The Graduate School, The Department of Agriculture. pp. 1–5.
- "Position Classification Standard for Quality Assurance Series, GS-1910" (PDF). US Office of Personnel Management. March 1983. Retrieved 21 December 2012.
- Juran, Joseph M., ed. (1995), A History of Managing for Quality: The Evolution, Trends, and Future Directions of Managing for Quality, Milwaukee, Wisconsin: The American Society for Quality Control, ISBN 9780873893411, OCLC 32394752
- Feigenbaum, Armand V. (1956). "Total Quality Control". Harvard Business Review. Cambridge, Massachusetts: Harvard University Press. 34 (6): 93–101. ISSN 0017-8012. OCLC 1751795.
- Feigenbaum, Armand Vallin (1961), Total Quality Control, New York, McGraw-Hill, OCLC 250573852
- Ishikawa, Kaoru (1985), What Is Total Quality Control? The Japanese Way (1 ed.), Englewood Cliffs, New Jersey: Prentice-Hall, pp. 90–91, ISBN 978-0-13-952433-2, OCLC 11467749
- Evans, James R.; Lindsay, William M. (1999),
The Management and Control of Quality (4 ed.),
Cincinnati, Ohio: South-Western College Publications, p.
The term total quality management, or TQM, has been commonly used to denote the system of managing for total quality. (The term TQM was actually developed within the Department of Defense. It has since been renamed Total Quality Leadership, since leadership outranks management in military thought.)
"What Is Six Sigma?" (PDF).
Schaumburg, Illinois: Motorola University. 19 February 2010. p. 2. Archived from
the original (PDF) on 3 December 2013. Retrieved 24 November 2013.
When practiced as a management system, Six Sigma is a high performance system for executing business strategy.External link in
- Wheat, B.; Mills, C.; Carnell, M. (2001). Leaning into Six Sigma: The Path to integration of Lean Enterprise and Six Sigma. Publishing Partners. p. 100. ISBN 9780971249103.
- Phillips, Joseph (November 2008). "Quality Control in Project Management". The Project Management Hut. Retrieved 21 December 2012.
- Rose, K.H. (2014). Project Quality Management: Why, What and How. J. Ross Publishing. p. 224. ISBN 9781604271027.
- This article incorporates public domain material from the General Services Administration document: "Federal Standard 1037C". (in support of MIL-STD-188)
- Radford, George S. (1922), The Control of Quality in Manufacturing, New York: Ronald Press Co., OCLC 1701274, retrieved 16 November 2013
- Shewhart, Walter A. (1931), Economic Control of Quality of Manufactured Product, New York: D. Van Nostrand Co., Inc., OCLC 1045408
- Juran, Joseph M. (1951), Quality-Control Handbook, New York: McGraw-Hill, OCLC 1220529
- Western Electric Company (1956), Statistical Quality Control Handbook (1 ed.), Indianapolis, Indiana: Western Electric Co., OCLC 33858387
- Feigenbaum, Armand V. (1961), Total Quality Control, New York: McGraw-Hill, OCLC 567344