GIF: Chelsea Beck

It’s a topic that’s polarizing for techies and Luddites alike: Is it ever truly okay to touch your laptop or desktop screen?

While smartphones and tablets definitely normalized the idea of putting our greasy sausage mitts on our expensive, beautiful gadgets, it’s still a point of contention. In the past it made sense to smack away hands reaching for displays, but more recently, 2-in-1 laptops and touchscreen monitors have blurred the lines between tablets and computers. In the Gizmodo office alone, the lines are clearly drawn between those of us who shudder at the idea of touching our screens, and those who don’t see it as a huge deal.

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So here’s the answer: It depends.

First there’s a matter of etiquette. If it ain’t your computer, don’t touch the screen. Doesn’t matter if your friend is a dunce and you’re trying to point out a specific part of an image or website—do not under any circumstances touch their screen unless you’re given express permission. This is doubly true if your friend doesn’t have a touchscreen device because then you’re just getting your finger oils all over a screen that doesn’t belong to you. It’s just manners!

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But what if it is a touchscreen and you have permission?

Again, it depends on the screen itself. There are multiple types of touchscreens, but the two you see most often are resistive and capacitive touchscreens. The former is the kind you’ll most likely find at a grocery store or bank when you have to sign your name with a finger or stylus at check out. They require a bit of pressure to register touch.

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On the other hand, capacitive touch screens are the type you’ll find in newer consumer electronics like smartphones, tablets, and yes, touchscreen laptops and monitors. These are built to be touched. They’re made of multiple layers of glass, and both inner and outer layers conduct electricity. Your finger alters the electrical current, which then lets the device detect the area you’re touching. This type of screen also allows for multiple touch points. And while you’ll get greasy fingerprints on it, you’re not actually going to cause any damage to the screen itself—unless perhaps you have some gnarly acrylic nails.

That said, it’s a totally different story for bare LCD screens. They differ from capacitive touch screens in that there’s less protection between the expensive parts of the display and your finger. An LCD, or liquid crystal display, is basically a layer of liquid crystal sandwiched between two sheets of polarized glass. The liquid crystal is made up of a bunch of rod-shaped molecules that behave both like a liquid and solid. Basically, this structure makes them reactive to electric currents, which can then let them transmit and changed polarized light. Put simply, electric signals ensure that the liquid crystals in each pixel—which consists of red, blue, and green cells—bend in the right way to project the correct image on your screen.

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This is why when you press a bare LCD screen that was never meant to be poked, you end up with ripples. You’re effectively displacing liquid crystal molecules and thereby distorting the image. Press too hard, and you can cause pixels to “stick”. Conversely, pressing hard is also a way to get stuck pixels to “unstick.” Still, too much pressure on an LCD screen can cause a crack and then you’re out of luck. And what about LED and OLED displays? Well, they are actually subsets of LCD screens—the basic technology is the same, the difference mainly lies in how the screen is lit. You won’t get ripples if you accidentally poke an LED or OLED, but you will if press down hard enough (though why would you??).

In reality, the occasional touch probably isn’t going to bork your screen. Still, the internet is full of forum posts by poor unfortunate souls who cracked their screens or ended up with dead pixels from some overenthusiastic touching. It can’t hurt to err on the safe side and remind friends—well-meaning or otherwise—not to touch your screen. Rule of thumb: If it’s not a touch screen, just keep your mitts off of it.

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