Hatha yoga
This is where you use controlled stretching that emphasizes the developing of a flexible spine. This is a good type of yoga for all levels of fitness.
Vini yoga
This is better yoga for people who are older. It is safe to do and is a gentle form or yoga. The teacher for this type of yoga is called a Desikachar.
Lyenger yoga
This form of yoga sometimes uses blocks and ropes because it focuses on correct postures.
Ashtanga yoga
This is also referred to as power yoga. You don’t want to do this type unless you like very demanding yoga. Only the people who are very fit will want to attempt this type of yoga.
For the people who want to be more spiritual:
Bikram
A series of 26 poses are performed in a heated room (the temperature can be anywhere from 90-100 degrees F) to make your body sweat. The heat in the room is meant to increase your body's flexibility, reduce the risk of injury and help you to detoxify.
Iyengar
This is a practice geared strongly toward bodily alignment. Poses are held for longer periods (as opposed to "flowing" from one into the other).
Power yoga
Similar to ashtanga, with a fast pace. Power yoga is for those looking for a vigorous workout and body toning.
Jivamukti
A physically intense yoga series that also involves chanting, meditation, and spiritual teachings.