Niyamas are 2nd of the 8-Limbs of yoga.
The Previous Limb -> The Yamas
Language
Sanskrit
Meaning:
Personal Ethics or Observances
The 5 Niyamas
Saucha - Purification
Santosha - Contentment
Tapas - Self-Discipline
Svadhyaya - Self-Study
Isvara Pranidhana - Surrender
Information
The Niyamas are personal disciplines which are things like having a daily practice, self-study. Trying to understand yourself is really part of the second limb of yoga and the discipline or the consistency of putting effort in toward understanding who you are and how do to evolve into a brighter more evolved version of yourself. In order to do that, you have to really understand where you are right now and come to an honest place about who you are in the world, which is what the first limb of yoga helps you to find. The Yamas and the Niyamas together help you to set the mind and the actions in the right direction before even beginning Asana, which is the third limb of yoga.
The Next Limb -> Asana
