"Sukha" means "pleasant" or "comfortable" in Sanskrit. Any cross-legged sitting position which you find comfortable, in which the body does not shake and in which you can remain at ease for a long time, is called Sukhasana.
Sit erect. Stretch out your legs loosely in front of you. Fold the left leg and draw in the foot towards the body. Raise the right knee and slide the left foot under the right thigh with the sole tilted up and touching the back of the right thigh near the knee. Similarly, fold the right leg and draw in that foot towards the body. Raise the left knee and slide the right foot under the left calf (not thigh) with the sole tilted up and the edge of the foot supporting the left shin. Rest the hands on the respective knees. Hold the head, neck and spine erect. Maintain this position as long as you like. Stretch forward both the legs and release the posture. The position of the right and the left legs could be interchanged.
This is the easiest of all asanas and the simplest of the crossed-legged postures and can be practiced by all. This is a basic sitting posture. You may start your daily yogic practices by first sitting in this position. This is a very comfortable posture and you may remain in it for long periods of time without any discomfort in the legs or pain in the knee-joints. The entire body will be at ease.