The Five Koshas in Yoga

Kosha means "sheath" in Sanskrit. In yoga, the term is used to describe metaphorical layers within the human body. This meaning comes from the ancient Hindu texts called the Upanishads. The koshas are often likened to Russian nesting dolls or the layers of an onion.

The outermost sheath is basically the physical body. It is the only layer that has an anatomical aspect. Although the other koshas are described as being layered, B.K.S. Iyengar explains in Light on Life (which uses the koshas as a framework) that the ideal is not for the layers to be clearly defined but rather for them to be seamlessly blended. This happens when there is optimal health and well-being. When things are out of balance, it becomes necessary to identify the kosha that is troubled and take on practices that may help it come back into harmony with the others. Exploring and integrating each layer brings your closer to a state of bliss.

1. Annamaya Kosha: The outer sheath is the body layer: muscles, bones, skin, organs.  Anna means food, which is what sustains this level. Asana keeps this kosha healthy and can be used to treat problems that arise in the body.
2. Pranamaya Kosha: The next sheath is the life force/energy sheath. It is concerned with the breath and the flow of energy through the body. Pranayama practice is prescribed to address this layer.
3. Manomaya Kosha: The next sheath is the mind or mental sheath. It has the do with thoughts and emotions. It is maintained through meditation. 
4. Vijnanamaya Kosha: is the knowledge sheath. This kosha is comprised of your wisdom, intuition, and perception. Meditation is also the key to this layer.
5. Anadamaya Kosha: The innermost sheath is the bliss sheath. It represents unending joy, love, peace, and complete happiness.

Like other elements of the subtle body (the chakras come to mind), the koshas are not meant to be interpreted literally. Instead, they provide an additional lens through which to view our experiences in the human body.