For thousands of years, yogis in India did sun salutations on the bare ground. When 20th-century Westerners first took up the discipline, the only cushioning they used on the hard floor was a blanket, a pillow or a piece of carpet, mostly to designate their personal space.
Now the popularity of yoga has left practitioners - 16.5 million in the United States alone, according to a 2005 Yoga Journal survey - with so many mats, and so much confusion. They come in cotton, synthetics and rubber. Some are thin, some are padded, and some are futon-thick. The environmentally conscious can also choose mats made with little or no PVC, the synthetic material that makes mats elastic but whose components are not entirely biodegradable.
Most of the newer mats, of course, are more expensive than the classic sticky mats found in gyms and yoga studios. Their nonslip surface and minimal cushioning still meet the needs of many for as little as $10.
Robyn Ross - a Manhattan-based yoga teacher who has created programs for New York City hospitals and has run a company called Life as Yoga for more than 13 years - recently tried a variety of postures on each of six mats to test them for comfort and grip. She suggested three things to look for in a mat: traction, cushion and personal comfort.