A Post-it note (or just Post-it) is a piece of stationery designed for temporarily attaching notes to documents, computer displays and so forth. A typical size is a 3-inch (7.5 cm) square, and they are traditionally yellow in colour, though they are now available in a wide range of shapes, sizes and hues. They have a strip of weak adhesive on the reverse which enables the note to be easily stuck and unstuck without leaving marks. The name "Post-it note" is a trademark of 3M, the company which invented and manufactures them.
History
The original adhesive used in Post-it notes was invented in 1968 by Spencer Silver, a 3M researcher. While attempting to design a strong adhesive, he instead developed an adhesive that was very weak. No immediate application was apparent, until 1974 when a colleague, Arthur Fry, conceived of using the adhesive to create bookmarks while contemplating a hymnal in his church choir. Initial prototypes were available in 1977, and by 1980–1981, after a large sampling campaign, the product had been introduced around the world.
A more recent innovation is software that partly mimics the behaviour of Post-it notes on the computer desktop. Most of the current proprietary or open source packages limit the placement or "adhesion" of the virtual note to a fixed spot over or on the desktop. A few permit sharing the notes through the Internet but none offer anything coming close to the flexibility of the sticky little piece of paper you can actually hold in your hands and place anywhere. Recent efforts like Project Looking Glass have striven towards features which give a virtual equivalence to the versatility of the tangible Post-it.
Earliest Post-It notes were glued to one side in a way similar to book binding. In recent years, 3M begin to manufacture Post-It pads glued on alternative sides. These pads can be installed on a dispenser.
In 1993, Saturday Night Live featured a fake product called McIntosh Post-It Notes, a parody of the failed Apple Newton.
In the 1997 film "Romy & Michele's High School Reunion", the two title characters attempt to re-invent themselves as successes to their former classmates by claiming to have invented Post-It notes.
In 2000 the 20th anniversary of Post-it notes was celebrated by having artists create their artwork on Post-it notes. One note that was made by artist R.B. Kitaj sold for $925 in an auction, making it the most valuable Post-it note in history.
In the 2003 film Bruce Almighty, Bruce makes all prayers materialize in the form of Post-It Notes, which cover every square inch of surface of the room he is in and everything in the room.
In the Showtime series Dead Like Me, Post-it notes are central to the plot of the show: the grim reapers receive their soul-taking assignments (first initial, last name, address, and estimated time of death) on Post-it notes. As a result, several characters are obsessed with Post-it notes.
In the final season of Sex and the City, lead character Carrie Bradshaw (Sarah Jessica Parker) is dumped by her boyfriend when he scribbles a message on a Post-it note.
In the 2003 Brad Anderson film The Machinist, the lead character is eventually led to the reason behind his insomnia and weight loss by a game of Hangman played on a Post-it note. Beginning in 2005, Post-it is a sponsor of Greg Biffle and the car 16 team of Roush Racing in the NASCAR Nextel Cup Series.