Conformance to requirements or fitness for use. Quality can be defined through five principal approaches:
1) Transcendent quality is an ideal, a condition of excellence.
2) Product-based quality is based on a product attribute.
3) User-based quality is fitness for use.
4) Manufacturing-based quality is conformance to requirements.
5) Value-based quality is the degree of excellence to an acceptable price.
Also, quality has two major components:
a) quality of conformance - quality is defined by the absence of defects.
b) quality of design - quality is measured by the degree of customer satisfaction with a product's characteristics and features.