Search bar: Android 4.0 features a Google search bar at the top of every home screen panel. You can tap here and begin typing a search term, or tap the Voice Actions icon on the right to initiate a voice search or perform other voice commands.
Home screen: You can fill this area with any combination of app shortcuts, folders and live, dynamic widgets (more on those in a bit). Android 4.0 gives you five home screen panels; just swipe left or right to move to the next or previous panel and access whatever you've stored there.
Favorites tray: The Favorites tray is like a dock for your home screen: The shortcuts or folders placed there stay present as you swipe from one panel to the next. By default, the tray includes commonly used items such as your Phone app, People app, Messaging app and Browser, with an icon for launching your app drawer in the center -- but you can customize it to include any items you want.
Navigation buttons: Instead of relying on a phone's physical buttons as in previous versions of Android, "ICS" has three main navigation buttons built into the interface at the bottom of the screen:
The Recent Apps tool allows you to multitask and switch among recently used applications. Click to view larger image.
The Back button, which looks like a left-facing arrow, takes you back one step from wherever you are.
The Home button, which looks vaguely like a house, returns you to your home screen.
The Recent Apps button -- a new addition to Android 4.0 -- allows you to multitask and switch among recently used applications. You can tap the button from anywhere in the system to get a list of recently used apps, then tap on any app to jump directly to that program. You can also swipe left or right on any app to dismiss it and remove it from the list.
If you've used Android before, you might be wondering what happened to the Menu button. As of Android 4.0, the Menu button is a thing of the past: All options and commands now appear on-screen instead of being hidden away like they were with previous-generation devices.
An icon that looks like three vertical dots contains additional functions relevant to your current activity. Click to view larger image.
If an application has more options than can fit on the screen, you'll see an icon that looks like three vertical dots; tapping that icon will bring up a list of additional functions relevant to your current activity.
(Curiously enough, the location of the vertical-dots icon is not always consistent, which was one of my criticisms of "ICS" in my initial review of the software.)
If your phone has hardware buttons: It's worth noting that while Google's Android 4.0 design guidelines call for virtual on-screen buttons, some phones still use hardware buttons instead -- either because they're older devices that have been upgraded or newer phones whose manufacturers have opted to stick with the older-style setup. If you're using an Android device that has physical buttons, those buttons should more or less correspond with the same functions described above.