Yoga is the cessation of the movements of the mind.
योग: चित्त-वृत्ति निरोध: (In Sanskrit ) ~ Patanjali Yoga Sutra 1.2
Yogaschitta vritti Nirodha
Maharishi Patanjali, the author of a famous yogic text ‘Yoga Sutra’ describes the whole purpose of yoga in just 3 words. Chitta or the mind stuff is constantly undergoing changes. These changes or fluctuations create thoughts, emotions leading to actions. Thus the purpose of yoga is, the cessation (Nirodha) of the fluctuations (Vrittis) of the mind (Chitta). It gives rise to the state of Samadhi where the mind is calm and undisturbed even in the most difficult circumstances. In order to reach a state of absolute calmness and balance, it is important to first develop an understanding of different states in which a human mind lies.
The 5 states of mind are: