When Booting-Up

Single User Mode
Keys: Apple + S
How to use it: Hold down these two keys from the beginning of bootup, this will eventually display a black and white screen with only a command prompt line. The purpose of this is for inputting UNIX commands via the keyboard. You must be comfortable with UNIX and be a very knowledgeable Mac user in order to use this feature, therefore it is not to be used lightly, if at all. To get out of Single User mode, type in reboot and press the return key.

Safe Boot Mode
Keys: Shift
How to use it: The computer is shut down, first of all, then press the power button. Immediately after you hear the startup tone, press and hold the Shift key. Release the Shift key when you see the gray Apple and spinning “gear”. During startup, you will see “Safe Boot” on the boot screen. To return to normal operation, restart the computer.

Boot from a CD-ROM disk instead of the hard disk.
Keys: c
How to use it: Hold down this key at the very beginning of bootup, when the Happy Mac screen is displayed.

Display the Boot Options screen (only on iMacs and all G4 Macs).
Keys: Option or Alt
How to use them: Hold down at the very beginning of bootup.

Deletes the contents of the PRAM memory file.
Keys: Apple + Option + p + r
How to use them: Hold down at the very beginning of bootup, until you see the screen flash or hear a beep.

Bypass the internal hard disk, and startup from a different System Folder.
Keys: Apple + Option + Shift + Backspace Delete
How to use them: Hold down at the very beginning of bootup.

Eject a floppy disk.
Action: Hold down the mouse button, right at the beginning of the bootup sequence, until it ejects the disk.

Restart or Shutdown the Mac via a dialogue box.
Keys: Apple + Option + Shift + Power key, or Power-key twice
How to use them: Press and hold all keys for 1-2 seconds, or press Power key twice in quick succession to display a dialogue asking if you want to shutdown, restart or cancel.

Immediately reboot the Mac.
Keys: Apple + Control + Power key
How to use them: Press and hold all keys for 1-2 seconds.

While in the Finder

Force quit any current program via a dialogue window.
Keys: Apple + Option + Escape
How to use them: Hold all keys down until a dialogue is displayed, this shows options for you to either; quit the program, or restart the Mac.

Hide current application.
Keys: Option/Alt
How to use it: Hold the option key when clicking on any other application’s windows or floating pallettes, this includes the FInder’s desktop.

Cleanup just the selected icons.
Key: Shift + Cleanup [menu]
How to use them: Highlight the icons, then press & hold the Shift key and select the menu item.

Sort and clean up selected icons.
Keys: Option + Shift + Cleanup [menu]
How to use them: Highlight the icons, then press & hold the key and select the menu item.

Edit the icon's filename.
Keys: Return or Enter
How to use it: Select one icon and press Return/Enter key, to go into edit mode.

Cancel a drag and drop operation.
How to use it: Drag the icon(s) over the menu bar and release the mouse button.

Select the next icon.
Key: Tab
How to use it: Press the Tab key once or multiple times.

Select the previous icon.
Keys: Shift + Tab
How to use them: Press the Tab key once or multiple times.

Select an icon that's nearby.
Keys: All Arrow Keys
How to use them: Press the arrow key in the direction of the icon you wish to highlight.

Select multiple icons.
Keys: Shift + Click left mouse button
How to use them: Press and hold the Shift key, then select each and every icon you need.

Unselect icons and folders.
Action: Click on the Desktop's Background
How to use it: Click the left mouse button once.

Closes all open windows and folders.
Key: Option + click on Close Gadget on (any window)
How to use them: Press key first and then the mouse button, on the close gadget.

Move window without making it active.
Key: Apple + drag window
How to use them: Press key first and then drag the window.

Automatically closes the folder's window when launching a document or application.
Key: Option + double click on application / icon / folder
How to use them: Press the Option key then double click the app/icon/folder.

Displays a contextual menu anywhere on screen (MacOS 8.0 upwards).
Key: Control + click [mouse button]
How to use them: Hold the Control key and click the mouse button, then select the option you require, from the menu.

Closes all open folder windows.
Key: Option + click on the window's close gadget
How to use them: Hold the option key, then click the gadget.

Copies the icon(s) into a different folder or location, leaving the original still in place.
Key: Option + drag icon
How to use them: Hold the option key, then click and drag the icon over the folder you want it duplicated to, and release the mouse button.

Creates an alias of the icon/folder/disk.
Keys: Apple + Option + drag icon
How to use them: Hold all keys, then drag & release mouse button.

Displays the folder's full path on the disk.
Keys: Apple + window title bar
How to use them: Hold key & click on the folder name in the window's title bar, a pop-up menu will appear.

A snapshot of the current Mac screen will be saved onto the root of the startup disk/partition.
Keys: Apple + Shift + 3
How to use them: Hold all keys until you hear a crunching sound, then the image will be saved.

Take a snapshot of any part of the Mac's screen.
Keys: Apple + Shift + 4
How to use them: Hold all keys down, then use the mouse to click and drag a rectangle round the area you wish to save, and release the mouse button.

A snapshot of any active window.
Keys: Apple + Shift + Capslock + 4
How to use them: Hold all the keys down, release them and use the mouse to click on the window you want.

Cancel current operation, this is equivalent to pressing the cancel button in a window. You may also use this key combo to cancel a disk request window.
Keys: Apple + . [full stop]
How to use them: Hold both keys down until the operation is cancelled.

Equivalent to clicking the OK button in a window. This also applies to all 'default' highlighted buttons (with extra thick border round it).
Keys: Return or Enter
How to use them: Just press the Return/Enter key once.

Save/Load Window

Cancels the save/load/overwrite dialogue box.
Keys: Apple + . [full stop] or Escape
How to use them: Press both keys together, until the window disappears.

Moves to the Desktop level, in the file requester window.
Keys: Apple + d
How to use them: Press both keys together.

Select the first file that begins with those letters.
How to use them: Type in the first 1-4 letters of the file.

Move down to the previous folder, in the file requester window.
Keys: Apple + UP arrow key
How to use them: Press both keys together.

Select the previous or next filename.
Keys: UP or DOWN arrow keys
How to use them: Press UP arrow for the previous file, and the DOWN arrow for the next file.

Open the selected file.
Keys: Return or Enter
How to use it: Press the key once.

Selects the No button in the "Do you want to save this document" dialogue box.
Keys: Apple + n
How to use them: Press both keys together, until the No option is selected.