Six Sigma is a business management strategy originally developed by Motorola. In 2009 widely applied in various industrial sectors, though the application is not without controversy.
Six Sigma aims to improve the quality of process outputs by identifying and removing the causes of defects (errors) and minimizing variability in manufacturing and business processes. Realized by using a set of quality management methods, including statistical methods, and creates a special infrastructure of people within the organization (“Black Belts”, “Green Belts”, etc.) who are experts in these methods. Each Six Sigma project carried out within an organization follows a defined sequence of steps and has made a calculation of the target. These targets can be financial (cost reduction or profit increase) or whatever is critical to the customer of the process (cycle time, safety, delivery, etc.).

Six Sigma originated as a set of practices designed to improve manufacturing processes and eliminate defects, but its application has been extended to the types of business processes as well. In Six Sigma, a defect is defined as a process output that does not meet customer specifications, or that could result in the creation process output that does not meet customer specifications.

Six Sigma heavily inspired by six decades of quality improvement methodologies such as quality control before, TQM, and Zero Defects, based on the work of pioneers such as Shewhart, Deming, Juran, Ishikawa, Taguchi and others.
Like its predecessors, Six Sigma doctrine asserts that:
* Ongoing efforts to achieve a stable process and predictable (ie reduce process variation) are very important for business success.
* Manufacturing and business processes have characteristics that can be measured, analyzed, improved and controlled.
* Achieving sustained quality improvement requires commitment from the entire organization, particularly from top-level management.
Features that set Six Sigma apart from previous quality improvement initiatives include:
* A clear focus on achieving measurable and calculated financial returns from any Six Sigma project
* Increased emphasis on strong management and passionate leadership and support.
* Infrastructure special “Champions,” “Master Black Belts,” “Black Belts,” etc. to lead and implement the Six Sigma approach.
* A clear commitment to making decisions based on verifiable data, rather than assumptions and guesswork.

The term “Six Sigma” comes from the field of statistics known as process capability studies. Initially, it refers 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 below 3.4 defects per million opportunities (DPMO). Implicit goal of Six Sigma is to improve all processes to a level of quality or better.
Six Sigma projects follow two project methodologies inspired by Plan-Do-Check-Act Cycle by Deming. This methodology consists of five phases each, which is abbreviated DMAIC and DMADV.
* DMAIC is used for projects aimed at improving an existing business process.
* DMADV is used for projects aimed at creating new product or process design.