AAC—Short for Advanced Audio Coding, this format is a competitor of the more common MP3 file format. It is the default format used by Apple.

Click Wheel—Apple’s proprietary circular control on the front of the iPod.

Certified For Windows Vista—A Microsoft certification that ensures portable devices, such as MP3 players, and media, such as digital music and videos, are compatible with each other. This was once called PlaysForSure.

download—In terms of digital music, downloading is when you retrieve a song from an Internet site or another network connection and save it to your computer or digital music player. You can download songs from music Web sites such as iTunes, Napster, or Rhapsody.

DRM (digital rights management)—A security mechanism for digital media, associated with copyright. A common DRM scheme for digital music involves getting a license file to authorize playback of a free or purchased song.

earbuds—Small, circular devices you put into your ears so you can listen to music on your player. These serve the same function as headphones. Many music players come with their own earbuds, but you can purchase a separate pair that are more comfortable or of better quality.

flash memory—Solid-state memory with no moving parts that is lightweight and small. In terms of digital music players, a flash-based player is lighter and smaller than a hard drive-based player, and it also won’t skip. Thus, flash-based players are popular for use during exercise. However, the capacity of a flash-based player isn’t as large as a hard drive-based player.

FM tuner—If your music player has a built-in FM tuner, you will be able to listen to music from local radio stations.

hard drive—Storage in which rigid platters are inside a fixed casing. In terms of digital music players, a hard drive-based player is larger and heavier than a flash-based player. Because of the moving parts (the platters), hard drive-based players are also prone to skipping. However, the capacities are much larger than those of flash-based players.

iTunes—An application that loads onto your computer and lets you play, organize, download, and purchase music, videos, podcasts, and television shows for your portable media player or computer.

MP3—Perhaps the most popular digital audio encoding format. It compresses audio to about one-twelfth the original size while still providing excellent sound. In general, a 1MB MP3 file will last about one minute.

playlist—A queue of songs a user creates to play on a computer, burn to a CD, or transfer to an MP3 player. The playlist includes only directions to the location of the songs, not the songs themselves.

podcast—A downloadable episode that is similar to a radio program. A user can subscribe to a podcast for updated episodes, or she can download podcasts one at a time.

screen—The display on the front of a portable music player. A player’s screen can either display in color or black and white.

WMA—Windows Media Audio is a digital audio format created by Microsoft.

widescreen—A screen with a 16:9 aspect ratio.