It also refers to a relational database table, a column, or a set of columns whose values identify one or more rows.
With a computer keyboard, a key is one of the keyboard’s buttons. Letters, numbers, functions, and symbols are all represented on keys.
When a keyboard key is pressed down, that key is sent as input to the computer and appears on the screen. Clicking the following box with your mouse and then typing any letter key on the keyboard makes it appear in the box.