Six Sigma is a business management strategy originally developed by Motorola in 1981.
Six Sigma seeks to improve the quality of process outputs by identifying and removing the causes of defects (errors) in manufacturing and business processes using a set of quality management methods.
It creates a special infrastructure of people within the organization ("Black Belts", "Green Belts", etc.) who are experts in these methods.
Each Six Sigma project follows a defined sequence of steps and has quantified financial targets.
In recent years practitioners have combined Six Sigma methods with Lean manufacturing to yield a methodology named Lean Six Sigma.