To do: get card for Post-It's 30th birthday

• A giant Post-it Note near London's Liverpool Street station celebrates the anniversary. Picture: PA

The Post-It note, on which a generation of us have salved our conscience by scribbling a "to-do" list which is rarely actually done, is now 30 years old.

The little yellow piece of paper with the sticky back may have evolved into digital versions but the actual product, inspired by a misbehaving book mark in a hymn book, continues to sell by the millions.

Over the past three decades the Post-It has been turned into an exhibit that decorated the Millennium Dome, been the basis for party games and, according to the BBC, one ambitious student has even written a thesis on them.

So where did the pads which now come in a rainbow of colours actually come from?

The genesis of the little sticky post-it began in 1968 when Dr Spencer Silver, a scientist with the American company, 3M, accidentally created a new form of adhesive. As a senior member of the company's Corporate Research Laboratory his role was to analyse glues and figure out how they could be applied to new products.

While experimenting he created a unique formula: an adhesive that formed clear, sparkly spheres, instead of a solid film, and so had a uniquely low-tack, or 'stickiness'. For five years he promoted the glue round the company, holding seminars on the subject but to little interest. However, in 1974, Art Fry, a product development engineer at 3M was singing in his church choir and growing increasingly frustrated that his book mark kept slipping, when he had the idea for a bookmark that was lightly adhesive.

He remembered Dr Silver's recent seminar and decided to develop a new product.

Fry and Silvers began work and as the lab next door to their office, in Cynthiana, Kentucky had scrap yellow paper, they decided to use this for the proto-type. By 1977 the final product had been prepared and was already a hit with office staff at 3M. In what became known as the 'Boise Blitz', the company decided to target office workers in the Idaho city by saturating the office supply industry with free samples, with the result that 90 per cent of those who tried it said they would buy it.

As a result it was introduced into 11 western states in 1979, and proved so popular that people began posting supplies to colleagues in states where it had not yet been released.

When the post-it was finally released across America in 1980 the company was inundated with letters of thanks, including from the chief executives of the largest companies in the country.

When the patent on the adhesive expired during the 1990s, a number of other companies produced similar products called 'sticky notes' or 'repositional notes', while 3M continued to enjoy market domination.

In 2003, the company launched a new product called Post-it Super Sticky notes, which used a much stronger glue which it allowed it to stick to a range of different surfaces.

Art Fry has retired, but still works part-time at the company. Previously he said the idea didn't make him rich but it made him happy and proud. "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. When Post-its are still used after I am gone, it will be as if a part of me will live on forever."