. Hatha yoga
In my opinion, this is the only ‘actual’ form of yoga. It is where [yoga] originated. In simple words, I’d say this is the one to nine of numbers. Everything after that is a combination of these numbers. Hatha means force, so this form is about building physical techniques that help you [preserve your energy]. 

. Iyengar yoga
This has been known to be therapeutic in nature, and helps in dealing with problems of the knees and the back. Practitioners use props that help them get into the asana easily, and it primarily helps them heal from physical injuries.