Problem
A default condition must be available for display once the device has started, and to return to when all other processes and applications have exited.
Solution
All mobile devices have an Idle Screen, originally when the device is not doing anything (it is idle). This is used as a launching point or when the user is not specifically asking anything of the device. This is akin to the desktop on a computer, and provides a method to access all the applications, services and and information stored on the device.
Do not confuse the Idle Screen with Lock Screen or any other seemingly default screen if it does not provide the same immediate access to available functions.
Variations
Most devices mix several design methods, in order to achieve all the needed goals.
The Idle Screen is the single screen which is loaded when the device is powered on, or when all applications are exited.
The Home Screens encompass all the device-level menus that contain links to the applications. The Idle Screen is invariably one of these Home Screens.
Home Screens may BE OF SEVERAL PATTERNS... LISTED!!!
***Either way: a screen of icons which when opened reveal drilldown menus, or the primary access is an icon field but additional features or the complete list of applications can only be accessed via a long list or drilldown.
A key variation is the addition of status information occupying a large portion of the screen. These have traditionally been fixed elements, or have only limited customization, but "widgets" are now supported on many devices, which may vary from interactive Icons to display or interactive elements that occupy a large portion of the screen.
Drilldown menu - S60 as archetype, but anything really - May be icons or text.
Field of items (usually icons) larger than the viewport. General method is a horizontal scroll to get to other "screens" and one is considered the Idle screen.
Some applications may appear to be continuous with the drilldown method of access. Settings, for example, should usually be considered an application, but the interface and interaction may be so seamless the user is unaware they have left the Home Screen drilldown and entered the Settings application.
Kiosks and similar constrained interfaces, which present a small number of fixed options are not different and still can be considered Idle Screens. They are simplified due to the regular influx of new users and the relatively low number of options offered.
A Lock Screen is not an Idle Screen, even if security policies load the locked state on exit from any application.
Interaction Details
drilldown, click to go... hardware key or SK/SK-like tab is back
For multi-page home screens: These are usually considered to be a single page larger than the viewport, and use the Film Strip pattern to access the several screens.
Modify screens; method (no single pattern) to add/remove/move items on the home/idle screens.
Very often, contextually-intelligent mobile devices should be presenting the last-used state to the user at all times, even after a power cycle. While the Idle Screen will still exist, it will be viewed much less in this case. Consider building interactive methods that avoid the Idle Screen, and allow continuous use of the device, instead of pogo-sticking from one application, to the idle screen, to another application.
Presentation Details
For drilldowns: Title pages subsidiary to the Idle Screen.
For multi-page home screens: These are usually considered to be a single page larger than the viewport, and use the Film Strip pattern to access the several screens.
Position: must be communicated scrollbar, or other scroll position indicators depending on what works best. Both for scrolling of lists in drilldowns, and for side-scrolling on multi-page home screens.
Antipatterns
F