The Post-It was really invented by two men, Spencer Silver and Arthur Fry, but neither of them set out to invent it.

In 1970 Spencer Silver was a lab research worker for 3M (the Minnesota Mining and Manufacturing Commany). As part of his job, he was trying to create a new and stronger adhesive. However, the only new adhesive he could come up with was even weaker than the one they produced already - it did stick, but you could easily pull it off a surface. So Silver gave up, though he kept the formula.

Another scientist, Arthur Fry, knew about the adhesive. In 1974 he wanted something to keep his place in his hymn book in church, but his book marks kept falling out. He remembered Silver's glue and put it on some paper bookmarks, thus creating the first Post-It. In 1980 3M began to sell them, and they are now top-selling products.

You can read the full story of the Post-It here.