1) What is Six Sigma (6S)?1.1 The concept The concept of sigma comes from the Greek letter 'σ' which statisticians use to describe the "standard deviation of a population ”. Thus, Sigma represents the variability within a population. Sigma's high level of quality demonstrates the possibility of defective products. The higher the Sigma level, the lower the defect rate. Therefore, the use of Six Sigma helps reduce variation, achieving small standard deviations and improving product quality. (Pande et al 2002, Breyfogle 1999, Breyfogle et al 2001, Oakland 1999)1.2 The Six Sigma background was developed by Motorola in the late 1980s with the aim of improving quality (Bhote 2002). In the 1990s, General Electric and Allied Signal successfully adopted Six Sigma. Subsequently, more and more organizations, first in the United States and then around the world, developed 6S and gained the attention of the business world. The Six Sigma strategy involves the use of statistical tools within a structured methodology to obtain the knowledge necessary to obtain faster, better and cheaper products and services from competitors. Disciplined and repeated implementation of the core strategy is the key to the 6S. (Breyfogle 1999, Urdhwareshe 2000)1.3 Definition of Six SigmaSix sigma has many definitions depending on the authors, it can be defined as a strategy, an operational initiative, a statistical method, a measurement tool, an objective, a comparative measure of performance , a vision, a philosophy and more. Breyfogle (1999) argues that Six Sigma is considered an operational strategy that uses a well-structured continuous improvement methodology. The aim is to reduce the variability of processes and the c......medium of paper......Six Sigma is not a technique or a method, according to the definition of Mario Perez-Wilson (1999), the 6S they aim for an optimized level of performance with almost zero defects in a process that produces products, services or transactions. Indicates the achievement and maintenance of world-class performance. Six Sigma is the outcome, not the journey. Consequently, Perez-Wilson does not view Six Sigma as a methodology, but as a goal. Consequently, according to Knowles (2011), as a result of the different visions, Six Sigma has three aspects and is: 1) A measure: how far is the organization from the goal and perfect quality? 2) An objective: 3.4 defects for a million opportunities.3) One philosophy: focuses on sustainability and a long-term strategy that aims to reduce expenses, decreasing variability in the process and products.