Answer:
Dozens of yoga types are practiced worldwide, but there isn't space here to review all of them, so I will limit my comments to Hatha, Kundalini, Bikram, and Ashtanga yoga, the four most popular types practiced in fitness centers and local yoga studios throughout the U.S.
I'll start by telling you that yoga has been around for millennia. According to some records, it was developed in Northern India over 5,000 years ago, and according to data published in 2004 in the journal Alternative Therapies in Health and Medicine, an estimated 15 million American adults have used yoga at least once in their lifetime, and more than 7.4 million participated in the year prior to when the research was conducted. Individuals interviewed for this research reported that they used yoga for wellness (stress reduction, quality of life), health conditions, and specific ailments like back or neck pain, and 90% felt yoga was very or somewhat helpful.
Hatha yoga is the most widely practiced type in the U.S. and is excellent for beginners. It is a gentle practice where you move slowly and smoothly through dozens of poses (called asanas). The focus is on holding the poses and integrating your breathing into the movement. Hatha is a great way to stretch, work your muscles, get in touch with your body, relax, and decrease stress. Iyengar yoga, a form of Hatha, uses similar poses but focuses more on body alignment and balance, holding poses longer, and using props such as straps, blankets, and blocks. Like Hatha it's also a good choice for beginners.
Kundalini yoga emphasizes rapid movement through the poses and emphasizes breathing, chanting, and meditation. It has a more spiritual feel than Hatha and focuses on energy balance in your body. Beginners unfamiliar with Hatha poses, chanting, and meditation, might find Kundalini more physically and mentally challenging then they are comfortable with and might want to start with Hatha.
Bikram yoga is practiced in a room (sometimes unventilated) heated to about 105 degrees Fahrenheit. The idea is that muscles will loosen and sweating will cleanse the body and remove symptoms of disease and chronic pain. To my knowledge, there hasn't been any research on the safety or efficacy of Bikram, and so I don't recommend it because of the potential risk of dehydration, blood pressure changes, and cardiac problems with exertion in such an inhospitable environment. This is particularly so for individuals who may have an existing heart problem or high blood pressure but don't know it. People who do it swear by it, and so if you are determined to try it, I recommend that you speak with your physician first.
Ashtanga, or power yoga, is designed to build strength and endurance. It is an aggressive workout where you move quickly from one pose to another. There is little emphasis on meditation with Ashtanga, and at the end of the session you will feel more like you have completed a traditional weight training or
callisthenic workout than you would with any other type of yoga. Ashtanga is for you if you're looking for a tough, physically challenging workout.