Six Sigma is a methodology to manage process variations that cause defects, defined as unacceptable deviation from the mean or target; and to systematically work towards managing variation to eliminate those defects[1]. The objective of Six Sigma is to deliver high performance, reliability, and value to the end customer. It was pioneered by Bill Smith at Motorola in 1986[2] and was originally defined[3] as a metric for measuring defects and improving quality; and a methodology to reduce defect levels below 3.4 Defects Per (one) Million Opportunities (DPMO). Six Sigma has now grown beyond defect control.
Six Sigma is a registered service mark and trademark of Motorola, Inc[4]. Motorola has reported over US$17 billion in savings[5] from Six Sigma to date.