Here is a basic synopsis of what white tea is from about.com:
From Sean Paajanen
I'm sure you've heard of black and green tea, but white?
Black tea has been fully fermented during processing, and green has not been fermented at all. Oolong teas are somewhere in the middle. So what is 'white tea'?
Well, just like those other teas, white tea come from the Camellia sinensis plant. But the leaves are picked and harvested before the leaves open fully, when the buds are still covered by fine white hair. Hence the name. White tea is scarcer than the other traditional teas, and quite a bit more expensive.
White tea is similar to green tea, in that it's undergone very little processing and no fermentation. But there is a noticable difference in taste. Most green teas have a distinctive 'grassy' taste to them, but white tea does not. The flavour is described as light, and sweet. You should steep white tea in water that is below the boiling point.
If you are drinking tea for your health, you may want to consider white teas. There is also considerably less caffeine in white tea than the other varieties (15mg per serving, compared to 40mg for black tea, and 20mg for green). Some studies have also shown that white tea contains more active cancer-fighting antioxidants than green tea.
As with all teas, there are many varieties of white tea, with poetic names such as: white peony, golden moon, silver needle and white cloud. White teas are produced mostly in China and Japan, but the Darjeeling region of India also produces some fine white teas.