Normally, your body sheds about 30,000 to 40,000 skin cells each day and replaces them with new ones. You don't feel the skin cells growing and shouldn't see any falling, or flaking, off.
The outer layer of your skin contains a mixture of dead skin cells and natural oils, which help it hold on to water. If this layer is damaged and moisture gets out, or if your skin cell renewal process goes off the rails, you could get flaky or scaly. Aging, exposure to sunlight and harsh chemicals, some medicines, and certain diseases could also be to blame.