The beautiful yoga poses we see are but one of the eight 'limbs' of yoga. There are seven additional core components to the practice, each of equal importance.
The components are like limbs in the sense that:
they all belong to the same body,
each one is essential,
one is not regarded higher than the other.
Together they form the framework for the yoga practice that ultimately brings unity of the mind, body, and spirit.
The eight limbs of Yoga are:
1. Yama: Ethics. Guidelines for interaction with others.
2. Niyama: Self-discipline. Rules for attitude and interaction with oneself.
3. Asanas: Physical postures.
4. Pranayama: Breathing exercises.
5. Pratyahara: Withdrawal of the senses. Non-attachment to external objects.
6. Dharana: Cultivating inner awareness and learning to focus our attention.
7. Dhyana: Meditation.
8. Samadhi: State of Oneness. Transcending the self, and realizing an interconnection to all living things.