My iTunes Shuffle Baker's Dozen 8-22-12

I'd love to know how the iTunes shuffle works. How exactly does it choose a song? Is it strictly random or is there some sort of pattern? At times, when it plays consecutive songs by the same artist or from the same album I'm especially curious. That didn't happen this time, though...

Lucky - Greg Kihn Band
Inner City Theme - Inner City
Quit Playing Games (With My Heart) - Backstreet Boys
Easier Said Than Done - Loose Ends
Your Love Keeps Working On Me (MK Brooklyn Mix) - Jody Watley
Brilliant Disguise - Bruce Springsteen
Footsteps - Lisa Stansfield
Sing (Harry Choo Choo Romero Club Mix) - Annie Lennox
You're Not Alone - Olive
Stay (Wasting Time) - Dave Matthews Band
This Old Heart of Mine (Is Weak For You) - The Isley Brothers
Lady, Lady, Lady - Joe Esposito
Lullaby of Clubland - Everything But The Girl