Although I use iTunes a lot, and have been using it since the very first version, I rarely have need to automatically repeat songs, or shuffle them. It's been so long, in fact, that I couldn't remember what the icons on the tool bar at in the iTunes footer stood for. I thought I'd write it up in case I forgot. Again. And frankly, I suspect I'm not in a minority.
You'll need to look at the bottom left of the iTunes window to find the icons; they're arranged under the Source list.
I'm not sure why, exactly, Apple chose to call this button Shuffle, using the verb associated most commonly with card games, instead of random, but they did. When iTunes is in Shuffle mode, the songs in the current Playlist or in the Library, depending on your current selection in the Source list, are played in a "random" order.
- To play songs in random order, click the Shuffle button at the bottom-left of the iTunes window. The button turns blue when Shuffle is selected.