The standing pose Virabhadrasana II (Warrior II Pose) is standard practice in most yoga classes. But few yogis know the tale of its genesis. It stems from ancient Hindu lore and the tales of the famous figure Virabhadra, "blessed hero"—which is typically rendered into English as "warrior."
Warrior II is the stance of a strong warrior. It is an excellent way to stretch your groins and, even though both feet stay on the floor, improve your balance. You can also, to a lesser extent, strengthen your arms and open your chest. Yoga master B.K.S. Iyengar points out in his book Light on Yoga that Vira II "tones the abdominals," and it's a nice way to strengthen your legs and make them shapely.
Above all, learning to stand strong in your standing poses empowers you to face whatever comes your way.