Pantheon Shell is a modular, DE-independent desktop shell.

It consists of:

• WingPanel - a panel that holds indicators and spawns application launcher
• Slingshot - a lightweight and stylish application launcher
• Pantheon Wallpaper - nautilus-free wallpaper service with smooth transitions and blur support
• Plank - dock, stupidly simple
• Cerbere - our watchdog, a simple service to relaunch all of the above if it closes or crashes (wouf!)

Unlike GNOME Shell or Unity, it's not monolithic "all-or-none" kind of thing. You can use some components from it while not using the others, or replace some of them with apps that suit you better.

Our philosophy of providing sane defaults and avoiding configuration applies here too. For example, to change the look of Wingpanel one has to edit CSS file - not a good thing to do for an average Joe, but provides great flexibility to the distributor.