Spark is an easy Hot Keys manager. A Hot Key is an action attached to a keyboard shortcut. With Spark you can create and organize Hot Keys that can be executed everywhere, whatever the foreground Application.
You can create different kinds of Hot Keys. Hot Keys that launch an application, open a document, control iTunes, execute an AppleScript,
etcÉ
For example, you are typing a document or reading a web page and you don't like the track played by iTunes, just type the "Next Track" Hot Key combination and
iTunes will play the next track, without come on the foreground and without you need move the mouse.
To know what append in the background, read How does it Work?.