Wikipedia
Shaucha (Sanskrit: शौच, also spelled Saucha, Śauca) literally means purity, cleanliness and clearness. It refers to purity of mind, speech and body. Saucha is one of the Niyamas of Yoga. It is discussed in many ancient Indian texts such as the Mahabharata and Patanjali's Yoga Sutras. It is a virtue in Hinduism and Jainism.
Saucha includes outer purity of body as well as inner purity of mind. The concept of Saucha is synonymous with Shudhi (शुद्धि). LePage states that Saucha in yoga is on many levels, and deepens as an understanding and evolution of self increases.
Shaucha, or holistic purity of the body, is considered essential for health, happiness and general well-being. External purity is achieved through daily ablutions, while internal purity is cultivated through physical exercises, including asana (postures) and pranayama (breathing techniques). Along with daily ablutions to cleanse one's body, the concept of Shaucha suggests clean surrounding, along with fresh and clean food to purify the body. Lack of Saucha, such as letting toxins build in body are a source of impurity.
Shaucha goes beyond purity of body, and includes purity of speech and mind. Anger, hate, prejudice, greed, pride, fear, negative thoughts are a source of impurity of mind. The impurities of the intellect are cleansed through the process of self-examination, or knowledge of self (Adhyatma-Vidya). The mind is purified through mindfulness and meditation on one's intent, feelings, actions and its causes.