Yamas are ethical rules. The five yamas listed by Patañjali in Yogasūtra
Ahiṃsā (अहिंसा): Nonviolence, non-harming other living beings
Satya (सत्य): truthfulness, non-falsehood
Asteya (अस्तेय): non-stealing[
Brahmacārya (ब्रह्मचर्य): chastity, marital fidelity or sexual restraint[
Aparigraha (अपरिग्रहः): non-avarice, non-possessiveness[
Niyama, are virtuous habits, behaviors and observances
Śauca: purity, clearness of mind, speech and body
Santoṣa: contentment, acceptance of others, acceptance of one's circumstances as they are in order to get past or change them, optimism for self[
Tapas: persistence, perseverance, austerity[
Svādhyāya: study of Vedas (see Sabda in epistemology section), study of self, self-reflection, introspection of self's thoughts, speeches and actions[
Pratyāhāra is a combination of two Sanskrit words prati- (the prefix प्रति-, "towards") and āhāra (आहार, "bring near, fetch").
Pratyahara is fetching and bringing near one's awareness and one's thoughts to within. It is a process of withdrawing one's thoughts from external objects, things, person, situation. It is turning one's attention to one's true Self, one's inner world, experiencing and examining self. It is a step of self extraction and abstraction. Pratyahara is not consciously closing one's eyes to the sensory world, it is consciously closing one's mind processes to the sensory world. Pratyahara empowers one to stop being controlled by the external world, fetch one's attention to seek self-knowledge and experience the freedom innate in one's inner world.
Pratyahara marks the transition of yoga experience from first four limbs that perfect external forms to last three limbs that perfect inner state, from outside to inside, from outer sphere of body to inner sphere of spirit.
Main article: Dharana
Dharana (Sanskrit: धारणा) means concentration, introspective focus and one-pointedness of mind. The root of word is dhṛ (धृ), which has a meaning of "to hold, maintain, keep".
Dharana as the sixth limb of yoga, is holding one's mind onto a particular inner state, subject or topic of one's mind. The mind (not sensory organ) is fixed on a mantra, or one's breath/navel/tip of tongue/any place, or an object one wants to observe, or a concept/idea in one's mind. Fixing the mind means one-pointed focus, without drifting of mind, and without jumping from one topic to another.
Main article: Dhyana in Hinduism
Dhyana (Sanskrit: ध्यान) literally means "contemplation, reflection" and "profound, abstract meditation".
Dhyana is contemplating, reflecting on whatever Dharana has focused on. If in the sixth limb of yoga one focused on a personal deity, Dhyana is its contemplation. If the concentration was on one object, Dhyana is non-judgmental, non-presumptuous observation of that object. If the focus was on a concept/idea, Dhyana is contemplating that concept/idea in all its aspects, forms and consequences. Dhyana is uninterrupted train of thought, current of cognition, flow of awareness.
Dhyana is integrally related to Dharana, one leads to other. Dharana is a state of mind, Dhyana the process of mind. Dhyana is distinct from Dharana in that the meditator becomes actively engaged with its focus. Patanjali defines contemplation (Dhyana) as the mind process, where the mind is fixed on something, and then there is "a course of uniform modification of knowledge". Adi Shankara, in his commentary on Yoga Sutras, distinguishes Dhyana from Dharana, by explaining Dhyana as the yoga state when there is only the "stream of continuous thought about the object, uninterrupted by other thoughts of different kind for the same object"; Dharana, states Shankara, is focussed on one object, but aware of its many aspects and ideas about the same object. Shankara gives the example of a yogin in a state of dharana on morning sun may be aware of its brilliance, color and orbit; the yogin in dhyana state contemplates on sun's orbit alone for example, without being interrupted by its color, brilliance or other related ideas.
Main article: Samadhi
Samadhi (Sanskrit: समाधि) literally means "putting together, joining, combining with, union, harmonious whole, trance".
Samadhi is oneness with the subject of meditation. There is no distinction, during the eighth limb of yoga, between the actor of meditation, the act of meditation and the subject of meditation. Samadhi is that spiritual state when one's mind is so absorbed in whatever it is contemplating on, that the mind loses the sense of its own identity. The thinker, the thought process and the thought fuse with the subject of thought. There is only oneness, samadhi.