"What is a Quality Circle? Definition and Examples"

Quality circles are noteworthy for many reasons: meta-, macro-, and micro-. These include, at the meta level, their contribution to the Japanese economic miracle; at the macro, their emphasis on self-organization as a pattern for managing project team work and their toolbox of design and problem-solving tools; and on the micro-, any given tool or construct, e.g. cause-effect diagrams.

Here is a concise and solid introduction, including a bit of historical context, presented via slide deck.