The "Num Lock" key is a feature found on most computer keyboards, particularly those with a numeric keypad. When activated, it allows users to input numbers using the keypad, making data entry more efficient. If Num Lock is turned off, the keys on the numeric keypad may perform different functions, such as navigation or editing commands. To toggle the Num Lock function, users can simply press the Num Lock key, usually located in the upper left corner of the numeric keypad. This key is especially useful for tasks involving spreadsheets or calculations, where quick number entry is essential.