Six Sigma is a set of methodologies that utilize data and statistical analysis to help eliminate defects and reduce variability in our products, processes and services.

Variability reduction at capacity constrained resources or money-bleeding problem areas is a key to success and increased throughput.
Six Sigma methodologies include DMAIC (Define, Measure, Analyze, Improve, Control) and DMADV (Define, Measure, Analyze, Design, Verify). The latter is a Design For Six Sigma (DFSS) methodology, and each methodology is applied as the individual situation dictates.

As the organization moves through the process of continuous improvement, it can get closer and closer to the true definition of Six Sigma quality : 3.4 defects for every one million opportunities.