The Dock is a ribbon of icons that normally spans the bottom of the Mac desktop. You can place the Dock on either side of the desktop if you prefer.
The Dock serves several purposes. You can launch an application from its icon in the Dock; check the Dock to see which applications are currently active; click a file or folder icon in the Dock to reopen any windows that you minimized; and add icons to the Dock for easy access to your favorite applications, folders, and files.
The Dock has two main sections, which are separated by a small vertical line or a 3D representation of a crosswalk, depending on which version of OS X you're using. Icons to the left of the divider represent applications; icons to the right of the divider represent windows and folders.
