What music formats does the iPod support?

All iPod models have an upgradable firmware that "enables support for future audio formats" and supported formats have changed over time. For details on the music formats supported at the time of release of any particular iPod, please refer to the specs page for the model of interest.

How can I use music encoded in WMA format with the iPod?

The iPod natively does not support WMA. If you are a Windows user and do not have the music available in another format, you will need to convert it to a format that the iPod can use, such as MP3. There are numerous applications that can quickly convert these files, such as SuperAudio Converter and WMA-to-MP3 Converter.

If there are other applications that you particularly like for this purpose, please share.

How "good" is the sound quality provided by the iPod?

In the official company FAQ, Apple says that:

iPod is designed to provide the best-quality sound. iPod has a powerful 60 mW amplifier so it can deliver audio as loud as you want. It also has a 20 Hz to 20 kHz frequency response, which means you can hear distortion-free music at the lowest or highest pitches.

Even the iPod headphones are designed to give you the best-quality sound. The earbud-style headphones rely on Neodymium transducers, a rare earth magnet that significantly enhances frequency response and overall sound quality. Most other headphones use aluminum, cobalt, or ceramic drivers; at the same size, the Neodymium driver is five times as powerful. Because the strength of the driver increases the accuracy of the sound, the iPod headphones provide a high-energy listening experience while minimizing distortion.

Regardless of Apple's claim of "best-quality sound", the iPod likely never will provide the sound quality of a high-fidelity stereo system, but can provide good quality sound in a relatively affordable and extremely convenient manner. The easiest way to improve the sound quality is to encode songs in a higher-quality format, such as Apple Lossless (not supported by the iPod shuffle models), or at a higher bitrate, such as 160 Kbps or higher.

Replacing the standard headphones with Apple's "In-Ear" headphones or higher-quality third-party headphones can also substantially improve the sound quality. Site sponsor OWC is a good place to start your search for enhanced headphones of your choice.

How does the iPod skip protection work?

From the official Apple iPod FAQ:

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.

This only applies to the full-sized iPod and iPod mini models. The iPod shuffle, iPod nano, and iPod touch models use solid-state flash memory, and consequently, cannot skip.

Can I remove the "gaps" between songs on the iPod?

Yes. Starting with iTunes 7, the program automatically scans all songs in its library and enables gapless playback for albums that were intended to not have silence between songs.

If iTunes 7 (or later) does not automatically recognize an album that you would like to have playback without gaps between songs, select all the songs in the album, select "Get Info" from the "File" menu, press "Yes" when it asks "Are you sure you want to edit information for multiple items?", select "Yes" under "Gapless Album", and press "OK".

Can I group songs or movements to "stick together" in shuffle mode?

No. If you have a need to play a group of songs or movements in a particular order (generally most applicable to classical music or "concept" albums), you will have to either listen to these songs "in order" rather than "shuffled" or import these songs/movements as one large music file.