Learn about common Mac OS X keyboard shortcuts. A keyboard shortcut is a way to invoke a function in Mac OS X by pressing a combination of keys on your keyboard.To use a keyboard shortcut, or key combination, you press a modifier key with a character key. For example, pressing the Command key the key with a symbol and the “c” key at the same time copies whatever is currently selected text, graphics, and so forth into the Clipboard. This is also known as the Command-C key combination or keyboard shortcut.A modifier key is a part of many key combinations. A modifier key alters the way other keystrokes or mouse clicks are interpreted by Mac OS X. Modifier keys include: Command, Control, Option, Shift, Caps Lock, and on portable Macs the fn key.