iPod offers three ways to transfer music from your computer. You can select one of the following update modes from the iPod Preferences menu in iTunes:

No, not at the same time. iPod is configured for either Mac or PC. You can use the iPod Software Updater utility to restore iPod to work with a Mac or a PC (depending on which version of the utility you use). See technical document 60983, "iPod: How to Restore" for more information.

If you have more music in iTunes than you can fit on iPod, you can choose to update selected playlists only or update manually. With the first option, only the tracks in the selected playlists (rather than the entire music library) are downloaded to iPod when you connect. With the manual update option, you manage what goes into your iPod by dragging and dropping selected songs or playlists into iPod.

iPod comes in many storage capacities from 5 GB to 40 GB. (See Note 2.) The amount of music iPod can hold depends on the compression rate of your songs. At 128 kilobits per second (kbit/s), the most common compression rate used for MP3s, 20 GB is equivalent to over 5000 four-minute songs, or more than 500 CDs. At the near-CD-quality 160 kbit/s compression rate, 20 GB equals over 4000 four-minute songs, or 400 CDs.

In addition to the hard drive, iPod has a memory cache. It is made up of solid-state memory, meaning that it has no mechanical or moving parts, so it is not affected by movement of the device. iPod skip protection works by preloading up to 25 minutes of music to the cache at a time. iPod plays music from the memory cache rather than the hard drive, so even rigorous activities won't cause music to skip.

An equalizer allows you to adjust various audio frequencies within the sound spectrum (much like the bass and treble controls on a stereo system). Equalization can be used to optimize audio playback for a specific room, genre of music, or individual's listening preference. The iPod comes standard with over 20 equalization presets, such as Jazz, Rock, or Bass Booster. Choose your EQ preset in the Settings menu.