Teleprompters look like magic on screen. a speaker delivers a polished script while staring directly at you. But the technology behind them is surprisingly simple, whether it's a broadcast studio rig or a free web app on a laptop.
The Original: Beam-Splitter Teleprompters
The classic teleprompter. the kind you see in newsrooms and on presidential podiums. uses a piece of glass called a beam-splitter mirror. Here's how the setup works:
- A monitor sits below the camera lens, facing upward. It displays the scrolling script.
- A sheet of glass is angled at 45 degrees between the monitor and the camera lens. This glass is coated so it reflects the text from the monitor while remaining transparent from the other side.
- The speaker sees the reflected text on the glass while looking directly at the camera lens behind it.
- The camera shoots through the glass as if it isn't there. The audience sees eye contact; the speaker sees their script.
Because the text on the monitor is reflected in a mirror, it needs to be displayed in reverse. this is why teleprompter software includes a "mirror mode" that flips text horizontally.
Why Do Teleprompters Use Mirrors?
For one reason: to put the script and the lens in the same place. Human eye-line is unforgiving. A viewer can tell when someone is looking a few degrees off camera, even if they could not tell you why the shot feels wrong. Reading from a screen next to the camera always reads as reading.
The mirror solves it by folding the light path. The monitor lies flat below the lens, out of shot, and the angled glass bounces its image up into the speaker's eyeline, directly in front of the lens. The speaker looks at the words. The camera, shooting through the same glass from behind, sees someone looking straight at it.
The reversal is a side effect, not a feature. Any mirror flips what it reflects, so the monitor has to display the script backwards for it to come out readable in the glass. That is the entire job of mirror mode.
Which also means you do not need a mirror at all if the camera is close. Put a laptop or tablet directly under the lens and the angle is small enough that nobody notices. Mirrors earn their keep when the camera is far back, as it is on a news set or at a podium, and even a small off-axis gap becomes visible.
Presidential Teleprompters
You've probably seen the two transparent panels flanking a podium during political speeches. These are presidential-style teleprompters — the same beam-splitter technology, but with two glass panels so the speaker can look left and right naturally while reading.
Each panel has its own monitor at the base. The audience sees clear glass; the speaker sees the script. The operator scrolls the text in real time, matching the speaker's pace.
Camera-Mounted Teleprompters
For studio and YouTube use, a smaller version of the beam-splitter rig mounts directly onto the camera. Products like the Elgato Prompter or Glide Gear TMP100 use the same principle. a monitor reflects text onto glass in front of the lens.
These rigs cost anywhere from $80 to $500+ and need a tablet or small monitor to drive the display. They work well in permanent studio setups but are bulky and impractical for creators who record in different locations.
How Online Teleprompters Work
Online teleprompters strip away all the hardware and give you just the essential part: scrolling text on a screen. Here's how a browser-based teleprompter like LilPrompter works:
- You paste your script into the web app
- You set the scroll speed . the app uses a smooth CSS or JavaScript animation to move the text upward at a constant rate
- You set the font size . large enough to read comfortably from your recording distance
- You hit play. the text scrolls smoothly while you read and record
Instead of looking through a beam-splitter mirror, you position your screen as close to the camera lens as possible. With a laptop webcam, the text is already right below the lens. With an external camera, you place a monitor or tablet beside it.
The result is nearly identical to a hardware rig for most video formats. In a talking-head YouTube video, the tiny difference in eye angle between "looking at the lens" and "looking just below the lens" is invisible to viewers.
Mirror Mode in Online Teleprompters
If you do use a beam-splitter rig, you still need software to display the scrolling text. Online teleprompters like LilPrompter include mirror mode. a one-click toggle that flips the text horizontally so it reads correctly when reflected off the glass.
Without mirror mode, the reflected text would appear backwards. With it, the same web app that works on your laptop screen also works as the display source for a hardware teleprompter rig.
What Controls the Scroll?
In a broadcast studio, a dedicated operator scrolls the teleprompter manually, matching the speaker's pace in real time. This is why live news looks so natural. a human is adjusting the speed moment to moment.
In an online teleprompter, you set the speed before you start and let it run. Good teleprompter software gives you fine-grained speed control so you can match your natural reading pace. Some paid apps add voice-activated scrolling that speeds up or slows down based on your speech. but for most creators, a fixed speed with a practice run is all you need.
Try It Yourself
The best way to understand how a teleprompter works is to use one. LilPrompter is a free online teleprompter . paste a script, set your speed, and hit play. No signup, no downloads, no hardware required.