Hatha is Sanskrit and translates as “Sun-Moon”. “Yoga” is the exact same meaning as “Yoke”. Together they refer to facing planets through which one can absorb various energies while doing specific postures and breathing exercises. The physical postures of Hatha Yoga whose main historic sources are attributed to India, particularly the Sutras of Patanjali- have become the stock-in-trade “Yoga Classes” of many an Athletic Club in the U.S.
I began with back bends at the age of ten with my mother coaching (“eventually you can touch your head with your heels” – and I did, unfortunately I did not keep practicing!) I eventually learned the basic postures from my Mime teacher, who insisted on using them to warm up. It was pretty intense – I was 18 at the time – but I was doing martial arts and found the stretching helpful, especially for high kicking. Later-I was 26- my wrestling teacher who had studied in India- insisted I begin to do Sun Salutation in high reps and he further advised me on other forms of Yoga. As the years passed I have come to believe any physical regimen is complemented by the Hatha Yoga postures. I prefer my own students do about six basic postures for general conditioning and recovery from the sprains and bruises of regular martial arts training. The DVD I sell is on these basic postures. One person recommended I do another and demonstrate the postures myself which I am considering doing. But it’s difficult to do it, explain it and point out the muscle sets!
For further research try to find Theos Bernard’s “Hatha Yoga” and Rammurti Mishra’s “Essential Yoga”. Most of the books on Yoga which are in print at present do not have the experience, depth or science of these texts.