Windows Dev Center

Windows.System namespace

Enables system functionality such as launching apps, obtaining information about a user, and memory profiling.


The Windows.System namespace has these types of members:


AppMemoryReport Represents app memory usage at a single point in time.
AppMemoryUsageLimitChangingEventArgs Provides data for the AppMemoryUsageLimitChanging event.
FolderLauncherOptions Specifies the options to use when launching File Explorer to display the contents of a specific folder by calling the LaunchFolderAsync(IStorageFolder, FolderLauncherOptions) method.
KnownUserProperties Contains basic information about a user.
Launcher Starts the default app associated with the specified file or URI.
LauncherOptions Specifies the options used to launch the default app for a file or URI.
LauncherUIOptions Specifies options for user interface elements such as the application picker that can be invoked by this API.
LaunchUriResult Represents the results of a Uri launch.
MemoryManager Provides access to information on an app's memory usage.
ProcessMemoryReport Represents process memory usage at a single point in time.
ProtocolForResultsOperation Represents the result to the application that launched the current application for results.
User Represents a user.
UserAuthenticationStatusChangeDeferral Represents a user authentication status change deferral returned by the UserAuthenticationStatusChangingEventArgs.GetDeferral method.
UserAuthenticationStatusChangingEventArgs Provides data for a user authentication status changing event.
UserChangedEventArgs Provides data for a user changed event.
UserWatcher Provides events that fire during enumeration of users, when the collection of users changes, or when a user's authentication status changes.



The Windows.System namespace has these enumerations.

AppMemoryUsageLevel An enumeration containing 3 levels of app memory usage: low, medium, and high.
LaunchQuerySupportStatus Specifies whether an app is available that supports activation.
LaunchQuerySupportType Specifies the type of activation to query for.
LaunchUriStatus Specifies the result of activating an application.
ProcessorArchitecture Specifies the processor architecture supported by an app.
UserAuthenticationStatus Represents the authentication status of a user.
UserPictureSize Represents user picture sizes.
UserType Represents user types.
UserWatcherStatus Represents the status of a user watcher.
VirtualKey Specifies the values for each virtual key.
VirtualKeyModifiers Specifies the virtual key used to modify another keypress.



The Windows.System namespace defines these interfaces.

ILauncherViewOptions Contains methods for launcher view options.



Minimum supported client

Windows 8

Minimum supported server

Windows Server 2012

Minimum supported phone

Windows Phone 8


Windows::System [C++]



See also

How to launch the default app for a file (JavaScript)
Launch the default app for a file
How to launch the default app for a URI (JavaScript)
Launch the default app for a URI
Association launching sample
Guidelines and checklist for file types and URIs



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