What is "vritti"

Vritti, literally "whirlpool", is a technical term in yoga meant to indicate that the contents of mental awareness are disturbances in the medium of consciousness. Vritti can be taken as a catch-all term for any content in consciousness, where consciousness is regarded as a medium or container for any possible mental content. The scope of the idea is very broad, referring not only to thoughts and perceptions experienced in a normal waking state, but also to all super-physical perceptions, such as dreams or in any altered state of consciousness. Vritti has also been translated as "waves" or "ripples" of disturbance upon the otherwise calm waters of the mind. The classical definition of yoga as stated in the Yoga Sutras is to calm the waves and return, or reunite (yoga = union) mind to its calm state, or samadhi.