Why do we start classes with Sun Salutations?
Sun Salutations are a traditional sequence of poses linked to breath that help to focus your mind, body and breath at the beginning of class. While Surya Namaskar A (Sun Salutation A) works to set the tone for your alignment throughout the class, Surya Namaskar B (Sun Salutation B) helps to build the internal heat that will allow you to push more deeply into your practice.
There are a variety of modifications that can help make these sequences accessible to a variety of experience levels and abilities. See below for traditional instructions by Rebecca Pachecco on how to do Sun Salutations.