Six Sigma is a set of techniques and tools aimed at process improvement. It was developed by Motorola in 1986 to reduce defects in manufacturing processes. Six Sigma seeks to improve quality by reducing variation and preventing defects. It uses a define-measure-analyze-improve-control methodology for process improvement projects. Key roles include Champions, Master Black Belts, Black Belts and Green Belts. While Six Sigma has helped many companies improve quality, some critics argue it is overused by consultants and may not achieve the benefits promised. Case studies demonstrate how Six Sigma has helped companies like LG Electronics and Catalent Pharma Solutions reduce defects and costs.