A teleprompter is also known as an autocue or a telescript. At its inception a teleprompter was simply a roll of paper that was “scrolled” in front of the performer or speaker as a way to “prompt” them of their lines. Technology has changed a lot since then.
Currently, a teleprompter refers to a monitor mounted below a piece beam splitter glass (a special mirror developed to shoot video through) that is enshrouded in either black plastic, metal or cloth to keep out the light. A camera is then placed behind the beam splitter glass and the video is shot through the mirror.
The teleprompter is then connected to a computer running teleprompter software that displays a mirror image of a script that scrolls at the talent’s own pace.
The talent is now able to deliver lines while looking directly into the camera lens (while reading the script shown in the teleprompter) giving the appearance of spontaneity.