Yoga is a non-competitive practice which cultivates strength, balance and coordination through controlled movement. It builds inner calm, awareness and respect for self and others while teaching inner stillness and awareness of each asana - its 12 basic postures or asanas - more than simply stretching exercises; their asanas open energy channels and chakras while strengthening bones, increasing circulation and improving immunity while cultivating forbearance and self-reliance and providing deep relaxation.
Yoga classes typically consist of moving through a series of asanas. Some are straightforward while others require great physical strength or balance skills. When practicing difficult asanas, uttava pranayama, or "deep breathing", must be used to prolong and hold poses for extended periods of time - this helps stimulate vital energy to flow throughout your entire body and relax and calm the nervous system.
As your body adapts to various postures, it will become easier for you to recall the first two limbs of yogic philosophy (yama and niyama) as well as meditation practice. Soon you may reach a point when your body no longer remembers that it exists!
Asanas may have their roots in Hatha Yoga, which was the primary branch of yoga until the 20th century. Around this time, B.K.S. Iyengar created postural yoga as it is practiced today in his 1966 book Light on Yoga that covers 200 asanas.