High-quality, DRM-free music. iTunes Plus is the new standard on iTunes.
Now,

you can choose from millions of iTunes Plus songs from all four major music labels and thousands of independents. With iTunes Plus, you get high-quality, 256-Kbps AAC encoding. All free of burn limits and digital rights management (DRM). So iTunes Plus music will play on iPod, Apple TV, all Mac and Windows computers, and many other digital music players. It’s also easy to upgrade your iTunes library to iTunes Plus. You don’t have to buy the song or album again. Just pay the 30¢ per song upgrade price.

(Music video upgrades are 60¢ and entire albums can be upgraded for 30 percent of the album price.)