The space bar, spacebar, or space key, is a key on an alphanumeric keyboard in the form of a horizontal bar in the lowermost row, significantly wider than other keys. Its main purpose is to conveniently enter the space

Space (punctuation)

In writing, a space is a blank area devoid of content, serving to separate words, letters, numbers, and punctuation. Conventions for interword and intersentence spaces vary among languages, and in some cases the spacing rules are quite complex....

, e.g., between words during typing

Typing

Typing is the process of inputting text into a device, such as a typewriter, cell phone, computer, or a calculator, by pressing keys on a keyboard. It can be distinguished from other means of input, such as the use of pointing devices like the computer mouse, and text input via speech...

. It is large enough so that a thumb from either hand can use it.

Depending on the operating system

Operating system

An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...

, the space bar used with a modifier key

Modifier key

In computing, a modifier key is a special key on a computer keyboard that modifies the normal action of another key when the two are pressed in combination....

 such as the control key

Control key

In computing, a Control key is a modifier key which, when pressed in conjunction with another key, will perform a special operation ; similar to the Shift key, the Control key rarely performs any function when pressed by itself...

 may have functions such as resizing or closing the current window

Window (computing)

In computing, a window is a visual area containing some kind of user interface. It usually has a rectangular shape that can overlap with the area of other windows...

, half-spacing, or even backspacing. On web browsers, the space bar usually allows the user to scroll down or to scroll up when the space bar is used with the shift key.

In many programs for playback of linear media, the space bar is used for pausing and resuming playback, or for manually advancing through text.