UVA and UVB are two categories within the ultraviolet range. UVA radiation has a wavelength between 320 and 400 nanometers, and UVB has a range of 290 to 320 nanometers. The more energetic UVB radiation is considered more dangerous to people, as it can lead to malignant melanomas. UVA can also potentially cause cancer, but is more likely to just cause unsightly wrinkles and leathery skin. This is why dermatologists and other physicians always recommend using sunscreen to prevent damage from ultraviolet radiation.