Everyone is only just working out what the lines on a keyboard are actually used for

It feels as though right now, every day on the internet is a lesson. I’ve just found out what the dots on a car windscreen are for, and now I’ve been told what the lines on a computer keyboard are for. It’s the practical things school never gave us.

A tweet has gone viral, asking what the lines found on the “F” and “J” keys are actually there for. The two keys have lifted bumps on them, and they actually serve a very helpful purpose. “I always wonder what these lines are for,” the tweet said.

Siempre me pregunto para qué son estas líneas pic.twitter.com/PiQXksZUEu

— itsD3lay🐧 (@itsD3lay) April 13, 2026

Well go on then, let’s find out.

So, what are the lines on a keyboard actually for?

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The bumps are there for the autopilot, fast typers among us. The small raised bumps or lines on the “F” and “J” keys are tactile markers. They are designed to help you find what is called the “home row” (ASDF and JKL;) for proper finger positioning without needing to look down at the keys.

The F and J keys are where your index fingers rest naturally on a QWERTY keyboard. So, these markers allow you to locate the starting position for all ten fingers, enabling efficient typing without even glancing at the keys. 

The lines on a keyboard can be helpful in lowlight situations, or if you don’t have a keyboard with any sort of back lighting. Or, if you’re copying from a document, or something else that might be taking your focus up on screen. You probably use them without even noticing!

Another day, another lesson.

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