The desktop is the background area on your screen, where you work with icons, folders, and disks. An icon is a picture that represents a disk, program, document, or folder. A window is a rectangle on the screen that displays the contents of a disk, folder, or document. For example, when you double-click a folder to open it, the folder's window opens and displays the items inside the folder. You use menus to choose a command to tell your computer what to do.
Menus reside in the menu bar at the top of the screen.
A dialog box is a window that appears when the computer needs your attention. The container where you drag files which you want to remove permanently . You can customize the items in this menu by adding or removing items from the Apple Menu Items folder. Locate an item on any local disk. You may view by small icon, icon, name, size, kind, label or date.