“In the search for a strong and permanent glue, Spencer Silver at 3M in Minneapolis found a weak and temporary adhesive instead. This was in 1968. Nobody could think of a use for it, until five years later a colleague named Art Fry remembered it when irritated by his place-markers falling out of a hymn-book while singing in a church choir. He went back to Silver and asked to apply the glue to small sheets of paper. The only paper lying around was bright yellow. The Post-it note was born.”

“In the search for a strong and permanent glue, Spencer Silver at 3M in Minneapolis found a weak and temporary adhesive instead. This was in 1968. Nobody could think of a use for it, until five years later a colleague named Art Fry remembered it when irritated by his place-markers falling out of a hymn-book while singing in a church choir. He went back to Silver and asked to apply the glue to small sheets of paper. The only paper lying around was bright yellow. The Post-it note was born.”

— Matt Ridley