Six Sigma is a business management strategy (Strategic management is an ongoing process that evaluates and controls the business and the industries in which the company is involved) originally developed by Motorola, USA in 1981. As of 2010, it enjoys a widespread application in many sectors of industry. The term "Six Sigma" comes from a field of statistics known as Process Capability Studies (The Process Capability is a measurable property of a process to the specification).
Originally, Six Sigma referred to the ability of manufacturing processes to produce a very high proportion of output within specification. Processes that operate with "six sigma quality" over the short- term are assumed to produce long-term defect levels. Six Sigma's implicit goal is to improve all processes to that level of needed quality or better.