The iTunes shuffle feature dances a random path through your iTunes music library, jumping from song to artist to album with no logic or order. Or does it? Some people swear that it does, others claim to see patterns all the time. But what's the truth?

The truth of how iTunes shuffle works lies in the spaces between our expectations, our perceptions, and our understanding of the difference between shuffle and random. What we may expect out of a "shuffle" feature is not necessarily what it's designed to do.

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How It Works

According to Newsweek's Steven Levy, who has written a book on the iPod and is one of the leading chroniclers of all things Apple, the shuffle feature works this way:

“When an iPod does a shuffle, it reorders the songs much the way a Vegas dealer shuffles a deck of cards, then plays them back in the new order. So if you keep listening for the week or so it takes to complete the list, you will hear everything, just once.”

But you must listen to the entire library all the way through without stopping for the randomness of shuffle to be perfect.

As Levy points out, most people don't listen to music this way. Instead, they reshuffle the "deck" constantly, creating new paths through their music libraries each time they listen on shuffle. This practice causes some tracks or orders of tracks to seem to repeat or group together.

Factors that Affect iTunes Shuffle Order

The shuffle order can also be affected by your individual settings. In iTunes Up Next mode, you can tell iTunes to play songs that are highly rated more often, which skews the randomness. Songs can also be marked "Skip When Shuffling" so that they're excluded from the shuffle mode.

Also, random chance—sometimes, songs will appear early in a reshuffle several times, thanks to the ironclad laws of probability.