Scroll lock

Scroll lock (or ScrLk) is the name of a key on a computer keyboard that was meant to lock all scrolling methods. The scroll lock key is rarely used and only came about because the original IBM PC keyboard had it. It was supposed to change how the arrow keys work. For example, when the scroll lock mode was turned on, the arrow keys would scroll the contents of a text window instead of moving the cursor. Today, the key doesn't do anything in most programs, and as a result, many keyboards today, especially those on laptops and mobile devices, do not have the scroll lock key.

Scroll Lock Media

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  The scroll-lock key with an activated indicator light on an IBM Model M keyboard.