Sticking around - the Post-it note is 20

Art Fry, the inventor of the ubiquitous Post-it note

The Post-it note, scourge of office cleaners and darling of list makers, is 20 years old.

The sticky label - thousands of which make up an exhibit in the Millennium Dome's work zone - was invented by scientist Art Fry in April 1980.

But its origins go back even further. In 1959, Dr Spencer Silver, a scientist at 3M, was experimenting with various adhesives. He created a glue that had a low-grade stickiness, but couldn't think of a use for it.

Fast-forward 21 years. Art Fry, a 3M employee who sang in his local church choir, was looking for a bookmark that didn't fall out of his hymn book.

No longer just in yellow

Frustrated by scraps of paper he had been using, Fry wondered how to get round the problem.

By experimenting with the adhesive formula that had been languishing in the company vaults since the 50s, he made a sticky marker that could be removed without damaging the pages of the hymn book.

The Post-it was born, 3M sold millions, and imitation notes are turned out by companies around the world.

Art Fry has now largely retired, but still works part-time at the company. The idea didn't make him rich but it made him happy.

Live forever

He's still proud of his invention. "They're used all over the Earth, and there are always improvements and additions to the line, such as tape flags, room decorator kits and flip charts.

"It's like having your children grow up and turn out to be happy and successful," he said.

"When Post-its are still used after I am gone, it will be as if a part of me will live on forever."

Initially, Art's notes only came in canary yellow pads, which matched the colour of American legal notepads.

Post-its have become an indispensable part of office life

Now, however, they come in all shapes and sizes, and over 30 different colours. Currently, the most popular hue is neon pink.

The most likely place for a note to be attached in the office is to the computer. In the home, you're more likely to find one stuck to the telephone (indecipherable scribbled message optional).

There can barely be a desk or office in the country which has not been swamped with the notes at least once.

Customised printed notes are also available, complete with a ready reminder of your choice.

From party games to academia

Post-its have been used as aids for party games, drinks coasters and makeshift flick books (see internet links on the right). And at least one ambitious student has written a thesis on them.

Even computers are not immune from their all-conquering status; various software companies produce electronic versions which float on the computer's screen, waiting to be adorned with pearls of wisdom.

The electronic notes have the advantage that they're not prone to becoming dog-eared, and always retain their stickiness.