AutoHide is a simple background application that will automatically hide applications after you switch out of them. This is convent if you work with applications that have many windows and switch between them often. AutoHide will automatically hide your other applications, reducing screen clutter and making a cleaner work environment.
To use AutoHide, just double click it. It is a faceless background application, so you won’t see its icon in the dock. It is recommended that you add AutoHide to your Login Items by going to the System Preferences Login pane and adding the application to the list. This way AutoHide will automatically launch when you login.
When you switch applications, the application you switch out of will be automatically hidden when AutoHide is running. You can override AutoHide on a per incident basis by holding the Bypass Key (default Shift) as you switch applications. AutoHide’s preferences are accessed by holding down the Apple key and moving your mouse to the top left corner of the screen. From here you can configure excluded applications, the hot corner of the screen and quit AutoHide.
This application is freeware and for those who switch constantly from app to app, it’s indispensable. Info here.