Quality is defined by the International Standards Organisation (ISO) as:
The totality of features and characteristics of a product or service that bear on its ability to satisfy stated or implied needs.
Quality can also mean "fit for purpose" and enforces the idea of "do it right the first time". The term quality is not used to express a degree of excellence in a competitive sense, not a quantitative sense for technical evaluations.
The objective of Quality Assurance (QA) is to give the customer exactly what they need on time, every time at the right cost. Quality Assurance provides the evidence needed to establish quality in work and that the activities involved in the quality process are being performed effectively.
Quality assurance covers all activities within the project, from design and development through to product integration and include Quality Control and Quality Management.
Quality control is a set of techniques that are used to fulfil the requirements for quality throughout a project and includes Configuration Management and Quality Management. Quality control activities are aimed at both monitoring a process and eliminating causes of unsatisfactory performance at relevant stages of the quality loop.
A Quality Plan is used to set out the specific quality practices, resources and sequence of events relevant to a particular project. The Quality Plan outlines the purpose of the project, roles and responsibilities of the project, project management overview, life cycle management, documentation produced by the project and how quality will be tested and checked throughout the life cycle using tools such as Audits, Inspections and Walkthroughs. The Quality plan will also specify how change management is handled and how code control is handled.
Quality Management includes strategic planning, allocation of resources and other systematic activities for quality such as quality planning, operations and evaluations.
The attainment of desired quality requires the commitment and participation of all members of the project.