In the nearly 30 years since it was introduced, Six Sigma has evolved to mean different things in different circumstances and in different organizations, so that now it is difficult to identify a single, universally accepted definition. The purpose of this note is to provide a basic overview of Six Sigma by explaining its underlying principles and most commonly utilized methods while providing a brief review of its history. Finally, this note provides a brief summary of a Six Sigma case study illustrating the practical application of Six Sigma.