As the preceding several thousand pages make clear, there are lots of ways to view and manage the seething mass of files and folders on a typical hard drive. Some of them actually let you see what’s in a document without having to open it—the Preview column in column view, the giant icons in Cover Flow, and so on.
Quick Look takes this idea to another level. It lets you open and browse a document at nearly full size—without switching window views or opening any new programs. You highlight an icon (or several) and then do one of these things:
Press the space bar. This is by far the best technique to learn. After all, unless you’re editing a file’s name, what’s the space bar ever done for you in the Finder? Nothing. But in OS X, you can highlight any icon and then tap the space bar for an instant preview.
Tap with three fingers. Here’s a bonus for laptops: Tap an icon with three fingers on the trackpad (don’t fully click down) to open its preview.
Press ⌘-Y. Another keystroke for the same function. The space bar is still better, though.
Click the icon at the top of the window. But who uses the mouse anymore?
Choose File→Quick Look.
Choose Quick Look from the Action menu () at the top of every Finder window.
Right-click (or two-finger click) an icon; from the shortcut menu, choose ...