Six Sigma is a data-driven approach and methodology for eliminating defects and improving processes. It uses statistical methods and tools to measure a process, analyze data, improve performance, and control processes. The main goals of Six Sigma are to reduce variation and defects in manufacturing and business processes. Key aspects include establishing a infrastructure with Champions, Black Belts, Green Belts and training. Successful Six Sigma programs at companies like Motorola and GE focused on measurable results, strong leadership support, and aggressive project selection.