The use of the terms “quality control” and “quality assurance” is not universal. In particular, the terms are applied differently in the public and private sectors.

For United States federal government suppliers, quality control (QC) includes the processes and procedures that a supplier uses to ensure that any supplies or services tendered meet contract requirements. In contrast, quality assurance (QA) refers to the methods that the government uses to determine whether the supplier has fulfilled contract obligations pertaining to quality and quantity. QA procedures are used to validate the supplier’s QC approach.

In the private sector, however, QA is defined as a procedure or set of procedures intended to ensure that a product or service under development (before work is complete, as opposed to afterwards) meets specified requirements. QC, on the other hand, is a procedure or set of procedures intended to ensure that finished products or performed services adhere to a defined set of quality criteria or meet the requirements of the customer.

Unless otherwise indicated, ThinkQ uses the terms and definitions for QC and QA as defined by the US federal government.

A Quality Management System (QMS) is the defined set of internal processes and procedures that enables an organization to fulfill its purpose and mission.  The QMS provides the organization with a comprehensive, executable approach to generating its products and services. The process of defining a QMS helps an organization to identify, measure, control, and improve its business processes. Instituting a QMS can significantly enhance an organization’s performance, potentially improving its market standing and competitiveness.

The term “quality” may have different meanings to individuals in differing circumstances. Perhaps the most common expectation of a “quality” product or service is that it meets certain pre-defined or generally well-accepted criteria.

The International Standards Organization (ISO) defines quality as “the degree to which a set of inherent characteristics fulfills requirements,” where “requirement” means need or expectation.

The influential management consultant Joseph M. Juran defined quality as “fitness for use,” with fitness being defined by the customer.

As defined by the American Society for Quality (ASQ), the term quality can mean “a product or service free of deficiencies.”

At the most basic level, the seller of any product or service has a moral (and usually contractual) obligation to meet or exceed the customer’s requirements for the intended or implied use of the product or service. As the management consultant Peter Drucker defined it, “Quality in a product or service is not what the supplier puts in. It is what the customer gets out and is willing to pay for.”

Ultimately, the responsibility for satisfying a customer’s quality expectations rests with the supplier.