You could be viewing this article on your laptop, phone, tablet, or desktop screen. No matter how you are reading it, you are viewing it through an interactive digital screen. The idea of electronic screens you can interact with is so normal to us that it can be easy to forget there was a time before them. Yet when computers were first invented, they did not have the classic monitors we think of today. Instead of viewing inputs and outputs on a computer screen, users could give the computer a punchcard, and only after a few days’ time, receive a printed report.

In 1963, working at the Stanford Research Institute, engineer Douglas Engelbert rethought the entire way computers work. With his team, he designed a computer called an On-Line System. Instead of users having delayed interactions with computers, he created a computer with a screen that users could manipulate and receive outputs from instantly.

But how would users control this new computer? The computer needed a way to track exactly what XY coordinate the user wanted to go to. Rather than having the user manually input this coordinate, Engelbert invented the computer mouse. The mouse tracked the movement of wheels, to correlate to a cursor on the screen. This allowed both the users and the computer to know exactly where the user was on the computer. Engelbert also added a button on the mouse, to allow users to click on the screen, controlling what the computer did.

The invention of the mouse was funded by the Advanced Research Projects Agency, the U.S. Air Force, and the National Aeronautics and Space Administration. This fundamental innovation created better, more useful computers. It paved the way for new ways of controlling electronics, including trackpads and touchscreens. Can you imagine if instead of having scrolled through this article, you needed a punchcard to read it?