Whose invention were Post-it Notes?

In 1968, 3M chemist Spencer Silver was trying to make a very strong glue but instead created microspheres of adhesive that stuck lightly and could be peeled off and reused. For years he promoted it inside the company without finding a product. In 1974 his colleague Art Fry, frustrated that paper bookmarks kept falling out of his church hymnbook, realised Silver’s adhesive could make a bookmark that stayed put without damaging pages. 3M test-marketed the notes as “Press ’n Peel” in 1977 with little success, then relaunched them as Post-it Notes in 1980. They became one of the best-known office products in the world.