EDINBURGH - Author J. K. Rowling yesterday marked the "wonderful" two decades since her Harry Potter creation first hit the shelves, starting a global literary phenomenon which has inspired a generation.

"20 years ago today a world that I had lived in alone was suddenly open to others. It’s been wonderful. Thank you," she wrote on Twitter.

A pair of rounded glasses and a lightning bolt accompanied the social media site’s special HarryPotter20 hashtag -- a nod to the boy and a zigzag scar, who emerged from a cupboard under the stairs to become the world’s most famous wizard.

Joanne Kathleen Rowling had struggled through poverty before winning a £1,500 publishing deal with Bloomsbury to print 1,000 copies of Harry Potter and the Philosopher’s Stone.

The seven volumes of the saga have since been translated into 79 languages and have sold more than 450 million copies worldwide -- and those lucky enough to have bought a first edition of Philosopher’s Stone have in their possession a collector’s book worth thousands.

"Harry Potter has had a huge impact on a generation of children, who became so obsessed with reading that they would queue for hours to get their hands on the next book," said Diana Gerald, head of the Book Trust, a charity which encourages youngsters to read.

Events to mark the magical tale include a special exhibition at the National Library of Scotland in Edinburgh, the city where Rowling penned much of the first novel.

"J. K. Rowling wrote the books just opposite, and just down the road as well, so it’s just really exciting to dress up and have some fun," said Francine Millard, 47, visiting the library in a Potter-themed scarf and carrying a toy owl.

Despite being just four years old when the first book was published, Kimberley Best said she was "obsessed" with Rowling’s magical world.

"My life is heavily influenced by it, it just brought me out of a bad time so it’s actually very important that I come and see it," she said, referring to a Philosopher’s Stone first edition on display filled with notes by Rowling.

Curator Graeme Hawley said the book was on loan from a private collector for the library’s "party" to mark a hugely important literary milestone.

"It’s become disproportionately significant in terms of its reach into modern children’s publishing, a total game-changer -- and the rest, as they say, is history," he said.

The Harry Potter empire has earned Rowling -- a committed philanthropist -- an estimated fortune of £650 million ($825 million, 743 million euros), according to The Sunday Times newspaper’s 2017 Rich List. — AFP