After months of rumors, Apple (NASDAQ:AAPL) has unveiled its new online music-streaming service, iTunes Radio. The free service will feature more than 200 stations and integrate with Apple's iTunes Store for purchasing songs. It will integrate among all devices, and evolve over time by playing music based on what users have already played or downloaded. iTunes Radio will also include exclusive previews from popular artists.

iTunes Radio. Source: Apple.

The streaming service will be entirely ad-supported, although subscribers to iTunes Match will not have ads at all. iTunes Radio has been considered a major threat to Pandora Media (NYSE:P), the first mover in online radio. Pandora shares dipped on the announcement, but have since recovered those losses.

iTunes Radio will launch this fall.