The shift key is a modifier key on a keyboard, used to type capital letters and other alternate "upper" characters. There are typically two shift keys, on the left and right sides of the row below the home row. The shift key's name originated from the typewriter, where one had to press and hold the button to shift up the case stamp to change to capital letters.
On an English keyboard, characters that typically require the use of the shift key include the parentheses, the question mark, the exclamation point, and the colon.
When the caps lock key is engaged, the shift key can be used to type lowercase letters on most systems.
On computer keyboards, as opposed to typewriter keyboards, the shift key can have many more uses:
- It is sometimes used to modify the function keys. Modern Windows keyboards typically have only 12 function keys; Shift+F1 must be used to type F13, Shift+F2 for F14, etc.
- It can modify various control and alt keys. For example, if Alt-tab is used to cycle through open windows, Shift-Alt-tab cycles in the reverse order.
- Holding shift while in a word processor will anchor the insertion point, such that moving the cursor and clicking the mouse to a new point will select the range of text in between.
- Holding shift while drawing with the mouse in graphics programs generally confines the shape to a straight line, usually vertically or horizontally.
- The shift key can also be used to modify the mouse behavior on a computer. For example, holding shift while clicking on a link in a web browser might cause the page to open in a new window, or to be downloaded.
- Holding shift while inserting a compact disc in a Microsoft Windows computer will disable the autorun feature. This ability has been used to circumvent the MediaMax CD-3 CD copy protection system.
- Holding shift while clicking on "Restart" in Windows will restart Windows and not the entire system.
- In Windows Explorer and some other file managers, holding shift while deleting a file will permanently delete that file rather than moving it to the recycle bin.
- In some Web browsers, holding shift while scrolling will scan through previously viewed Web pages.
- In Mac OS X, pressing the shift key while performing certain actions, such as minimising a window or enabling/disabling Dashboard or Exposé, makes the animation occur in slow motion. For some animations, holding Control will make the animation move just slightly slower, and holding Control and Shift will result in an extremely slow motion animation.
On some keyboards, if both shift keys are held down simultaneously only some letters can be typed. For example, on the Dell keyboard Model RT7D20 only 16 letters can be typed. This phenomenon is known as "masking" and is a fundamental limitation of the way keyboards are designed.
On some Apple keyboards, the key is indicated by an outlined up-pointing arrow (U+21E7, ⇧), which is also used in menus to describe the shortcut key. On others, the word “shift”, or a combination of the two, is used.