From Tadasana, weight is shifted to one leg, for example, starting with the left leg. The entire sole of the foot remains in contact with the floor. The right knee is bent and the right foot placed on the left inner thigh, or in half lotus position. In either foot placement, the hips should be open, with the right knee pointing toward the right, not forward. With the toes of the right foot pointing directly down, the left foot, center of the pelvis, shoulders and head are all vertically aligned. Hands are typically held above the head either pointed directly upwards and unclasped, or clasped together in anjali mudra.
The asana is typically held for 20 to 60 seconds to stretch the spine, returning to tadasana while exhaling, then repeating standing on the opposite leg.
This article uses material from the Wikipedia article "List of asanas", which is released under the Creative Commons Attribution-Share-Alike License 3.0.