Yoga is self awareness resulting in a union of mind, body and soul. While Yoga itself is a way of being, the Yoga practices are methods to help guide us into the self awareness that unites our entire being. Yoga classes tend to focus on the practice of postures (asana), shapes we create with our bodies which combine physical alignment with mental alertness and awareness of breath.
Practices help strengthen and tone our muscles and can increase flexibility around the joints, but also boost the flow of healing energy (prana) through energy channels (nadis) which nourishes us on all levels.