1. Wite-Out
Remember being a student and writing reports? Back in our day, we had to type our reports, and when we made a mistake, we either had to cross out the typo, or start again. Then they came out with Wite-Out. It was revolutionary! It was kind of messy, and if you were making a carbon copy of your report, it was time-consuming letting it dry. But overall, it was a lifesaver for students.