Extend vs duplicate display: which should you use?
Windows gives you two ways to use a second screen, and they do opposite things. Here's the difference in plain English, and when each is the right one.
Duplicate: the same picture on both
Duplicate (also called "mirror") shows exactly the same thing on every screen. Move a window on one, it moves on the other. It's the right choice when other people need to see what's on your laptop, presenting in a meeting room, plugging into a projector, or a booth screen. The downside: both screens are locked to the lower resolution of the two, and you get no extra working space.
Extend: one big desktop across your screens
Extend treats your monitors as one continuous desktop, so you can spread windows across them and drag things from one to the next. This is what you want for actually working — email on one screen, your document on another, a browser on a third. Each screen keeps its own resolution. This is the default most people are reaching for when they plug in a second monitor.
Which should I use?
- Working at your desk? Extend. More space is the whole point.
- Presenting to a room, or on a projector? Duplicate, so everyone sees your screen.
- Meeting booth where you also want private notes? Extend, and put the room screen where the wall is (your notes stay on the laptop).
How to switch between them
The quick way is Windows key + P, which opens the Project panel: PC screen only, Duplicate, Extend, or Second screen only. Or go to Settings → System → Display and pick from the "Multiple displays" drop-down.
The catch: choosing Extend doesn't put your monitors in the right order, or set the correct primary screen. So you extend, then still end up dragging the numbered boxes around to match your desk — and at a shared desk it lands differently every time.
The one-click version
ScreenSwytch picks the right mode and sorts the rest in a single click. Choose On a Desk and it extends your monitors in the correct order with the right primary; choose Meeting Room and it offers duplicate or extend, placed to match where the room screen actually is. No Win+P, no dragging boxes.