The sigma in Six Sigma refers to the Greek symbols, which designates a standard deviation in statistics. The six refers to the number of standard deviations from a mean specifications should be.
From the early days of improving the robustness of design at motorola. Six Sigma has morphed into an organization-wide program for improvement involving hierarchical training, organizational learning, and pay for learning.
Six Sigma is an advanced quality improvement approach designed to tackle most quality problems. We use the DMAIC process. DMAIC stands for define, measure, analyze, improve, and control.