Programs To Access System Resources

1.    Unity
All GUI-based operating systems use a desktop environment. Desktop environments contain many features, including (but not limited to):
The look and feel of the system
The organization of the desktop
How the user navigates the desktop
Ubuntu uses Unity as the default desktop environment. The Unity desktop is comprised of the desktop background and two bars—a horizontal one located at the top of your desktop called the menu bar and a vertically oriented bar at the far left called the Launcher.
2.    The Desktop Background
Below the menu bar at the top of the screen is an image covering the entire desktop. This is the default desktop background, or wallpaper, belonging to the default Ubuntu 14.04 theme known as Ambiance. To learn more about customizing your desktop (including changing your desktop background), see the section on customizing your desktop below.
3.    The Menu Bar

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The menu bar incorporates common functions used in Ubuntu. The icons on the far-right of the menu bar are located in an area of the menu bar called the indicator area, or notification area. Each installation of Ubuntu may contain slightly different types and quantities of icons based on a number of factors, including the type of hardware and available on-board peripherals upon which the Ubuntu installation is based. Some programs add an icon to the indicator area automatically during installation.
4.    The Launcher
Thevertical bar of icons on the left side of the desktop is called the Launcher. TheLauncher provides easy access to applications, mounted devices, and the Trash. All running applications on your system will place an icon in the
Launcher while the application is running. To change the Launcher icon size, go to Session Indicator  System Settings  Appearance, tab Look.
The first icon at the top of the Launcher is the Dash, a component of Unity. We will explore the Dash in a later section of this chapter. By default, other applications appear in the Launcher, including the Files file manager, LibreOffice, Firefox, any mounted devices, and the Trash, which contains deleted folders and files, at the bottom of the Launcher.
5.    Running applications
To run an application from the Launcher (or cause an already-running application to appear), just click on the application’s icon. Applications that are currently running will have one or more triangles on the left side of the icon indicating the number of application windows open for this application. Running applications also have a back-lit icon on the Launcher.
6.    Adding and removing applications from the Launcher
There are two ways to add an application to the Launcher:
Open the Dash, find the application you wish to add to the Launcher and drag its icon to the Launcher.
Run    the application you    want to add to the    Launcher, right-click on
the application's icon on the Launcher, and select Lock to Launcher.
To remove an application from the Launcher, right-click on the applica7tion’s icon, then select Unlock from Launcher.