Discovering a new bookshop is always a delight, but getting to know Abebooks.com is a reader's paradise, writes Mary Leland

When is a website more like a world? When it's Abebooks.com. The seductiveness of this site can become addictive, but in an era when the best books disappear even from library shelves to make way for more recent publications, it seems sometimes that Abebooks is a consolation as well as a resource. It is a fund of friends, some old, some to be rediscovered, some as yet unknown.

I can only excuse, or at least explain, my addiction by giving an example: now that the children are having children themselves it's time to sort out the bookshelves. Boxing the volumes to be sent to this new generation of book-lovers, I find among the favourites The Story of Holly and Ivy, by Rumer Godden. A slight enough work, it has to be said, but as its author has written so much and so well, the book has to be included among the beloved emigres. Paging through it, thinking that this is perhaps for the last time, I study every paragraph back and front, and in a note about the author see a reference to her translation of Prayers from the Ark, by Carmen Bernos de Gasztold (1963). Never having heard of either book or writer I go to my favourite website and a week later hold in my hand the hardback 1964 reprint by Macmillan, illustrated by Jean Primrose.

This delightful edition has come from Bardic Books in Armagh at a total cost, including postage and packaging, of about €10. There is no age-limit on readers; it is not specifically for children. But as it is so difficult to get good, sensitively written and well-illustrated books for children on biblical themes, this is a little treasure (the 26 prayers are from the cat or the cricket, the ox or the dove, the goldfish, the elephant, the ant, and begin with Noah's own prayer) and naturally now one has to be found for each of the grandchildren. But at least I know where to look for them, lurking as they are among the 100 million titles on the Abebooks catalogue.

It has its complications, of course. There is the mysterious language: does it matter if the spine is bumped? Or if the front hinge is shaken, the date uncertain, if there is a book-plate or inscription on the frontispiece? What is the meaning of "ffep"? Does a slight tanning matter, and does o/w mean otherwise? Otherwise - a good clean tight copy (but what does "a reading copy" mean?) is an encouraging sequence in the often bewildering code of the listed booksellers. Thanks to UCC archivist Carol Quinn, I already know that "foxing" is that speckled effect found sometimes in old books. The quarterly magazine, Slightly Foxed, therefore reveals itself as lightheartedly devoted to literary commentary - although the quality of its contributors, from Penelope Lively, Dervla Murphy and Miranda Seymour to Peter Oborne and John Saumarez Smith, indicates that "light" isn't a pejorative term here.

It's in the introduction to a 2007 issue of Slightly Foxedthat the mention of The Difficulty of Being a Dog, by Roger Grenier, occurs, in reference to the death of the magazine's in-house spaniel, Jennings. And in Abebooks.com the book, translated by Alice Kaplan, presents itself in a reassuringly available list. So does Lavender's Blue, an anthology of nursery rhymes collected by Kathleen Lines, illustrated by Harold Jones and available in various editions from €0.73 (OUP paperback, 1990). Hearing this title mentioned on the radio I had to stop the car to write it down. Now - if that way inclined - I can get a first edition (1954) from Sillan Books in Cootehill, Co Cavan, for €65. It's much more likely that I'll go for the 2004 facsimile hardback edition on offer at Blackwell Online in Oxford for €22.93, although I'm also drawn to Hollett and Son in Cumbria, who describe their 1960 edition as having illustrations in the "typical soft Harold Jones palette . . . A lovely work". It must be, as Toby Books, in Haslemere in Surrey, remarks that its 1965 edition (€15.29) "unfortunately . . . has been a school library copy and has been handled by children. Despite this the pages are remarkably clean . . . a fabulous collection". Handled by children - what more could be asked of a compilation of nursery rhymes with its wonderful pictures?

It was Nicola Beuaman, author of a study of women novelists from 1914-1939, A Very Great Profession, who put me on to Abebooks. Her London shop, Persephone Books, seemed to be a likely source of Angela Thirkell titles; it was not, but the staff recommended the website from which I have now garnered nearly all the Thirkells I want. This wickedly humorous writer is mannered and limited and has to be taken in small doses - but those doses are effective tonics. Having discovered Abe (which booksellers seem to call, with some affection, Aby), I sought a significant christening gift and found it in a Nonesuch Press edition of the 1611 King James Bible, designed by Francis Meynell, in three volumes with 16th-century woodcuts by Bernard Salomon, all for €75. Its baffled three-month-old recipient may not have been thrilled to bits - but in time, in time, he will be. Won't he?

"Aby is a great help, it gets me widely known," says Christine Tulk, whose Drumwood Books in Tipperary provided a long-desired hardback edition of Stay Me With Flagons, by Maurice Healy (1939). A member of the Irish association of antiquarian booksellers, Tulk has been selling books only for four years and now opens a stall at the car-boot sale in Fethard every Sunday. "I've always loved books but had so many of them that I had to find a way to make room for new ones," he says. "Once I started trading, I found I enjoyed it - you get a very discriminating clientele. I've been a member of Abebooks for more than two years now, so people know about me. It gets everything out there."

Here's where to find crime-writer Richard Stark, also known as Donald Westlake, whose most recent book, Ask the Parrot(2007), may or may not be in the bookshops. It's certainly in Abe, along with a crowd of his other titles. There's also a list of John P Marquand. A recent review of two new biographies of the poet Shelley mentions that "the greatest literary biography of modern times" was Shelley: The Pursuit, by Richard Holmes. Abebooks confirms this opinion, quoting Stephen Spender, and offers 23 copies from UK sellers alone. The sellers have their own home pages, the ordering, payment and confirmation process is streamlined for PC-users, and there is a kind of excitement too in dealing with shops and sellers whom one will never visit, whether in Australia, South Africa, America, Canada or Europe. Abebooks opens a world.

Now I try to decide between two delicious copies of Elizabeth Gaskell's Cranford. One, from Silver Trees Books near Coventry, is in a pale-green cover with gilded spine, published in 1904 and exquisitely illustrated by CE Brock (about €12 including postage); the other is from Cotswold Internet Books in Cheltenham, its navy cover tooled and gilded, dated 1907, with tinted pictures by Hugh Thompson and with an introduction by Anne Thackeray Ritchie (€15). These are for gifts - the dithering decision is which to send to whom. My own copy of Cranford is dated 1902, illustrated by TH Robinson and is, I must admit, both inscribed and slightly foxed. But, until Abe, I never thought it mattered.

Apart from Angela Thirkell, my searches are all for books I think other people, from infants to adults, should be given. And high on that list is The Ginger Tree, by Oswald Wynd. Let's see: there is the distraction of The Ginger Tree, adapted by Christopher Hampton, to be dealt with first, but then Oswald Wynd, aka thriller-writer Gavin Black, comes up in Worldofbooks.com in Goring by Sea, or Hurley Books in Mevagissey, or the Chapter House in Suffolk, or TomTom Books in Hastings which, offers a first edition from 1977 or - I might go for this - Elvis Shakespeare in Edinburgh . . . Abebooks.com is more than a world, it's a reader's paradise.

Aidan Dunne is on leave