Upward Facing Dog is one of the 12 poses in the Sun Salutation (Surya Namaskar). It is a favorite of mine to limber up the back and feet while opening up the heart and throat chakras.
Ideally, only the tops of your feet and the inside of your hands and fingers touch the mat or ground. Everything else is lifting up as you arch your back and stretch the neck. It's important to keep the shoulders down, back, and relaxed, despite the weight and tension they are carrying.
As mentioned in my book, "From the Boxing Ring to the Ashram: Wisdom for Mind, Body and Spirit," people with herniated disks will often benefit from back-bending yoga poses like this one. However, consult your doctor first. With herniated disks in particular, it's important to know which way the herniation is before you do either back bends or forward folds.
Additionally, in my book, I mention the importance of core strength to minimize some chronic low back pain. This pose stretches many of the back muscles while strengthening the lower back muscles and stimulating the abdomen.