iTunes can run in three size modes: small, medium, or large (Figure 8-1). Here's where you'll find them:
Large. This size is what you see the first time you open iTunes.
Medium. You can switch back and forth between large and medium sizes by clicking the green zoom button or choosing Window → Zoom. Either way, the medium mode is handy for playing tunes in the background while you work without your screen being overtaken.
Small. If your desktop isn't big enough for even the medium iTunes window in Figure 8-1, try taking it down a notch. To create the mini-window shown at lower right in Figure 8-1, start with the medium-size window and drag the Resize handle (the diagonal lines in the lower-right corner) leftward. To expand it, just reverse the process.