The Alt key Alt on a computer keyboard is used to change (alternate) the function of other pressed keys. Thus, the Alt key is a modifier key, used in a similar fashion to the Shift key. For example, simply pressing A will type the letter 'a', but holding down the Alt key while pressing A will cause the computer to perform an Alt+A function, which varies from program to program. The international standard ISO/IEC 9995-2 calls it Alternate key. The key is located on either side of the space bar, but in non-US PC keyboard layouts, rather than a second Alt key, there is an 'Alt Gr' key to the right of the space bar. Both placements are in accordance with ISO/IEC 9995-2. With some keyboard mappings, the right Alt key can be reconfigured to function as an AltGr key although not engraved as such.

The Shift key ⇧ Shift 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.