When I first used OS X, I wondered what all this fuss about Growl was. Having switched from Windows, no such universal cross application alert system existed.
However, I soon grew to use and depend on it until now, I can't imagine OS X without it. Growl is basically an alert tool which can be used by hundreds of applications to inform you that an action has just taken place. So for example, when using Spotify, Growl alerts will let you know when a new track has started with a discreet pop up message in the top right of your screen.
Alternatively, Growl can be used to tell you when a download has been completed, a user has logged onto a messaging client and just about anything that involves notification. Of course, an application has to support Growl in order to use it. Some applications can, however, have Growl support added to them using plug-ins or 'extras' which can be found in a folder in the installer.
Growl alerts are highly customizable. You can choose a range of display styles, select which corner of the screen you want to display alerts, and select how long to leave notifications on the screen among many other things. You can even change the opacity of alerts. All of these settings can be accessed using the Growl preference panel installed in the System Preferences.
Growl is a must-have notification tool for Mac users. It's the easiest, slickest and most convenient way to keep track of what's going on on your system.
