The Ashtanga Vinyasa Yoga is a style of yoga codified and popularized by K. Pattabhi Jois during the 20th century which is often promoted as a modern-day form of classical Indian yoga. Ashtanga means eight limbs or branches, of which asana or physical yoga posture is merely one branch, breath or pranayama is another. Both Pattabhi Jois and Sharath Jois, his grandson, encourage practice of Ashtanga Yoga - all eight limbs. The first two limbs - Yamas and Niyamas - are given special emphasis to be practiced in conjunction with the 3rd and 4th limbs (asana and pranayama). Sri K. Pattabhi Jois began his yoga studies in 1927 at the age of 12, and by 1948 had established the Ashtanga Yoga Research Institute for teaching the specific yoga practice known as Ashtanga (Sanskrit for "eight-limbed") Yoga. Ashtanga Yoga is named after the eight limbs of yoga mentioned in the Yoga Sutras of Patanjali. "Power yoga" and "vinyasa yoga" are generic terms that may refer to any type of aerobically vigorous yoga exercise derived from Ashtanga yoga.