Libnotify provides an API for presenting notifications to the user. Notifications can be simple messages or they can allow the user to respond. For example, Empathy (GNOME's instant-messaging software) uses notifications to tell the user when he gets an instant message. Notifications made with Libnotify will use the appropriate interface in the environment the application is running in: in GNOME 3, notifications are displayed at the bottom of the screen and then put into the messaging tray, while other desktop shells may choose to show them differently.