When on-camera talent performs, they read what they speak from a teleprompter. Traditionally, this task is performed by a dedicated computer with an application to edit and scroll the text at a user driven speed using a piece of hardware called a "scroller". The Video output of the scrolling text is reflected from a half silvered (pellix) mirror and the camera shoots through the other side of the mirror so that the talent is looking into the camera but reading the reflection of the text.
This requires lots of hardware and software to achieve the same results as Prompt and a laptop computer or computer monitor. By placing the laptop computer between the talent and the camera the talent can read text from the top of the laptop screen and still appear to be looking at the camera if the camera is far enough back using a long lens. Trial and effort is the key to getting a natural look to this process but the further the camera is from the subject, the better. If the talent will be controlling their own scrolling then mouse control is the best and if you have long mouse cord, that's even better. There is a built-in function to allow someone else to control the speed by using the keyboard or mouse. Use both if you like. Prompt also mirrors the text and displays at multiple resolutions.