Six Sigma is a data-driven methodology and set of tools and techniques used to improve business processes and reduce defects or errors in products and services. It was originally developed by Motorola in the 1980s and has since been widely adopted by many organizations in various industries, including manufacturing, healthcare, finance, and more.

The term "Six Sigma" refers to a statistical measure of process performance. In a Six Sigma process, the goal is to achieve a level of performance where there are no more than 3.4 defects per million opportunities (DPMO). This level of performance corresponds to a process that is 99.9997% defect-free.