What are the 8 folds of yoga?

Yama [moral codes]
Niyama [self-purification and study]
Asana [posture]
Pranayama [breath control]
Pratyahara [sense control]
Dharana [concentration]
Dhyana [meditation]
Samadhi [contemplation

For more on this see http://www.ashtanga.com/html/background.html