What is Expose?

Exposé is an awesome feature of the Mac OS X user Interface that makes it easy to see, access, or hide application windows and documents. It's a great feature to help you work with the clutter that tends to build up when you are using multiple applications and/or documents.

Find it Fast
Ok, so you've opened numerous applications, documents, and Finder windows. Your screen is cluttered and you need to switch to another application or find that other If you invoke the "All windows" action Exposé will show you a miniaturized version of each window or document. You can then click on the item you'd like. Cool!

Image from Mac OS X Leopard

Image from Mac OS X Tiger

By pressing a specific hot key or moving your mouse to a specific area of the screen you can invoke Exposé. Mac OS X will darken the Desktop and highlight all open windows ( that have not been minimized to the Dock) and kick off a sleek animation. All open windows and documents shrink into highlighted thumbnails and reposition themselves allowing you to see everything in clear view. Another feature allows you to hide everything and quickly display the Desktop.

Expose can be invoked to perform three actions with either a hot key or click of the mouse. Some users refer to these as "Modes".

All Windows
Application Windows
Show Desktop

Note that Mac OS X ships with default hot keys to invoke the actions but these can be configured by you in System Preferences.

All Windows
The "All Windows" action will work on all open windows and documents. By default, this action is invoked by pressing the F9 key. You can click on any window/document to make the active window and application or hit the Tab key to cycle through all applications and their corresponding windows. Just see how the Menu Bar changes.

Application Windows
The "Application Windows" action will work on the current active application to reveal all open windows/documents for that application. Let's say you have five Safari windows open and you want to see them all. Just hit the F10 key.

Desktop
The "Desktop" action moves all open windows and documents to the edges of the screen to display the Desktop underneath b pressing the F11 key.

Review - In a default Expose configuration:

F9 tiles all open application windows
F10 tiles all open windows for the current application
F11 hides all open windows allowing you to view the Desktop

You can customize Exposé via System Preferences and change these keys. The following shows what the Exposé settings in System Preferences. Note that the column on the the right is where you can a mouse button to invoke one of the three Exposé actions. Read the Expose Preferences guide for more details.