Concept
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; the shift key was first used in the Remington No. 2 Type-Writer of 1878; the No. 1 model was capital-only. On the US layout and similar keyboard layouts, 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 may be used to type lowercase letters on many operating systems, though not on macOS. The keyboard symbol for the Shift key (which is called Level 2 Select key in the international standard series ISO/IEC 9995) is given in ISO/IEC 9995-7 as symbol 1, and in ISO 7000 “Graphical symbols for use on equipment” as a directional variant of the symbol ISO-7000-251. In Unicode 6.1, the character approximating this symbol best is U+21E7 (⇧). This symbol is commonly used to denote the Shift key on modern keyboards (especially on non-US layouts and on the Apple Keyboard), sometimes in combination with the word “shift” or its translation in the local language. This symbol also is used in texts to denote the shift key. 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 Microsoft 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, and using Ctrl-Shift-S could open a "Save as..." dialogue allowing to choose a new file name and directory instead of overwriting the current file.
