Book excerpt: Six Sigma has taken the corporate world by storm and represents the thrust of numerous efforts in manufacturing and service organizations to improve products, services, and processes. Although Six Sigma brings a new direction to quality and productivity improvement, its underlying tools and philosophy are grounded in the fundamental principles of total quality and continuous improvement that have been used for many decades. Nevertheless, Six Sigma has brought a renewed interest in quality and improvement that few can argue with, and has kept alive the principles of total quality developed in the latter part of the 20th Century.