Question: what does anti ghosting mean on a keyboard

title: Rollover (key)
text: During normal typing on a conventional computer keyboard , only one key is usually pressed at any given time , then released before the next key is pressed . However , this is not always the case . When using modifier keys such as Shift or Control , the user intentionally holds the modifier key ( s ) while pressing and releasing another key . Rapid typists may also sometimes inadvertently press a key before releasing the previous one . Certain unusual forms of keyboarding require multiple keys to be pressed or held down simultaneously ; for example , Braille2000 keying requires as many as six keys to be pressed at once analogous to the six dot keys of a Braille typewriter . Some computer games require keys ( other than the usual modifier keys ) to be held down while others are pressed and released .