Āsana: postures designed to awaken and purify the body. Postures are selected to relieve physical stressors and change patterns of movement that are unhealthy. Mindful movement into and out of postures is coordinated with the breath. Once the body is at ease, we are in a better state for deep breathing and meditation.
Prāṇāyāma: breathing -- long, smooth breaths, coupled with asana or seated breathing techniques and ratios. Each of the Prāṇāyāma techniques alters the quality of energy in the body via breath development and pacing. Prāṇā means life force energy and āyāma means to extend. Breathing is a powerful energetic tool, considered to be the link between the body and the mind.
Sound (mantra, ancient Vedic chants and Yoga Sūtras of Patañjali): work with our system on a deeper energetic level than āsana and prāṇāyāma. Chanting sounds that mean something insightful to an individual can be healing and transformational. The vibrations of these ancient sounds reach profound dimensions of us.
Nyasa: hand placement and gestures that bring attention and connection to breath phases or parts of the body.
Meditation (dhāraṇā, dhyāna, samādhi): is another definition of yoga and also a means for reaching a state of yoga. An object of meditation can be an image, concept or mantra that contains the qualities we are seeking.