The Shift Key is a modifier key found on computer keyboards, typically labeled as "Shift." It is used to change the function of other keys when pressed simultaneously. For example, holding down the Shift key while typing a letter will produce an uppercase letter, while pressing it with a number key will often yield a special character, such as "!" or "@". In addition to altering letter case, the Shift key can also be used in combination with other keys to perform various functions. For instance, it can help select multiple items in a list or enable shortcuts in software applications like Microsoft Word or Adobe Photoshop.