When you first start your Apple Mac computer, and wait for it to finish doing everything, you finally get to the Desktop Screen. The desktop screen is made up of three sections, with the main section being covered with desktop icons; as shown in Fig 1.1 below.
Fig 1.0 The Menu Bar
Fig 1.1 The Desktop Icons
Fig 1.1 The Dock (Taskbar)
An icon is simply an image that is designed to represent a file, or folder, so that you have some idea of what that file does or what is inside the folder. For example:
An icon with a Document image might be representing the text (data) file itself or the Word Processor application (program) file that created the text. Whereas an icon with a Paint Brush image might be representing the drawing (data) itself or the Paint Application (program) file used to create the drawing. An icon with a Folder image though normally represents a folder and more importantly what is inside that folder (i.e. photo files, music files and/or text files).
When you double click (press the left mouse button twice, quite fast on the same spot) on an icon, OS X first determines what file is associated with that icon - an application (program) file or a data (i.e. music, photo or text) file. So if you double click on the Microsoft Word (W) icon for example OS X will only launch the application (program) called Microsoft Word (Microsoft Word.app) - It will not go on to open WORD Document (text file). It will just display a blank page (blank document).
If the icon you double click on is associated with a particular WORD Document, called John_Cairns.docx for example, OS X will first launch (open/run) the application called Microsoft Word (Microsoft Word.app) before instructing it to automatically open the WORD Document (John_Cairns.docx) in order to display its content (i.e. text, drawings and charts).
The Dock is basically an Icons Toolbar for application files, equivalent to the Microsoft Windows 7 Taskbar. It's a place where certain applications (programs) can park their associated file icons, otherwise known as docking their icons. And furthermore, parking and unparking their icons or docking and undocking their icons.
When you want to launch (open/run/execute) an application whose icon is docked (parked) on The Dock you only need to click on that application's docked icon once in order to launch its application file (the application file associated with the icon). For example. If you click the left mouse button once when the mouse pointer is over the Microsoft WORD icon (the W icon) the application file called Microsoft Word.app is launched.
Clicking on the W icon launches (opens) the application file called Microsoft Word.app
The docked (parked) W icon will bounce to let you know the application file called Microsoft Word.app is opening
The docked (parked) W icon has a faint white glow underneath it to denote Microsoft Word is now open
The above shows that after clicking on the W icon its associated application (Microsoft WORD) is ready. In other words, Microsoft WORD has launched with a blank document (or the Template Gallery); ready for you to start typing something onto it. When you minimize (collapse) the document's window (explained in other sections) an icon that represents that opened document will be placed on the right-side of the dock, to the left of the TRASH icon.
The opened MS WORD doc (window) has been minimised (collapsed), denoted by the W icon (far right).
The above W icon, to the left of TRASH icon, tells you that a Microsoft WORD document (its window) is currently minimised (opened, but not viewable in front of you). If you click on that minimised W icon once its associated Microsoft WORD document (window) will become maximised again (in full view).
Clicking on the W icon, to the left of TRASH icon, will maximise (full view) the MS WORD doc (window) again.
You will know the Microsoft WORD document (window) has been maximised (brought into full view) because its W icon to the left of the TRASH icon will have disappeared.
The MS WORD doc (window) has been maximised - Its W icon, to the left of the TRASH icon, has disappeared.
If you close (exit) the Microsoft WORD document (its window) the document itself (Passwords in this case) will close, after any necessary saving of it, but the
Microsoft Word application file (Microsoft Word.app) will remain open (launched). This is denoted by the faint white glow underneath the main W (application file)
icon. It is only when you quit the actual application (Microsoft WORD in this example) that it will really be closed down.
Put another way; When you open an application such as Microsoft WORD in Windows 7, you open a new/blank document, type something into it, save it and then exit Microsoft WORD. In which case the document and the application (program) are closed down. With OS X though, when you close a document for example you are only closing that document. The application (Microsoft Word.app) is left running, just in case you want to use that application again. This is something Windows 7 users might find strange! So when you know you have finished with an application you should get into the habit of closing it down completely, manually by clicking on its docked icon for about 2 seconds and then clicking on its QUIT menu-item.
Click on the Microsoft WORD docked icon for 2 seconds and then click on the QUIT menu-item
The Dock and The Desktop are explained in the Windows section and throughout this website in general, so don't worry if some of the above flew past you as more examples and explanations will make things clearer.