White tea comes from the delicate buds and younger leaves of the tea plant. These buds and leaves are allowed to wither in natural sunlight before they are lightly processed to prevent oxidation or further tea processing. This preserves the mild flavor of the tea, with almost no astringency or bitterness. If you've only had white tea in teabags, you've never really experienced white tea. It is called "white tea" because of the fine silvery-white hairs on the unopened buds of the tea plant, which gives the tea a whitish appearance.
White teas tend to be sweeter than green teas, and are high in catechins and antioxidant polyphenols. They are not necessarily low in caffeine, despite the urban legends. Tea plants tend to concentrate their caffeine in the newer growth (it's a natural insecticide), which is what's used for making the higher-quality white teas, so some are actually quite high in caffeine.
Steep your white tea longer than most other teas (4-7 minutes is typical), and use cooler water. Boiling water will ruin a delicate white tea. Try to keep the water at under 175 degrees.
White teas can be infused more than once.