Invention of Post-it Notes by Arthur Fry and Spencer Silver in 1974

Everyone knows what Post-it® notes are: They are those great little self-stick notepapers. Most people have Post-it® Notes. Most people use them. Most people love them. But Post-it® Notes were not a planned product.

No one got the idea and then stayed up nights to invent it. A man named Spencer Silver was working in the 3M research laboratories in 1970 trying to find a strong adhesive. Silver developed a new adhesive, but it was even weaker than what 3M already manufactured. It stuck to objects, but could easily be lifted off. It was super weak instead of super strong.

No one knew what to do with the stuff, but Silver didn't discard it. Then one Sunday four years later, another 3M scientist named Arthur Fry was singing in the church's choir. He used markers to keep his place in the hymnal, but they kept falling out of the book. Remembering Silver's adhesive, Fry used some to coat his markers. Success! With the weak adhesive, the markers stayed in place, yet lifted off without damaging the pages. 3M began distributing Post-it ® Notes nationwide in 1980 - ten years after Silver developed the super weak adhesive. Today they are one of the most popular office products available.

Source: http://www.ideafinder.com/history/inventions/postit.htm