The mid 19th century saw two interesting developments: the invention of the book jacket and the ‘Penny Dreadful’, a type of British fiction publication in the 19th century that usually featured lurid serial stories appearing in parts over a number of weeks, each part costing a penny.

In 1832 detachable book sleeves, or dust jackets, were introduced. Such sleeves are important to collectors, as books with their sleeves intact are of much higher value than those without them, and the condition of a dust jacket can hugely affect the value of a book.

The ‘Penny Dreadful’ was the first mass-market paperback, aimed at the juvenile working-class market and featuring horror and crime stories for a penny each. Paperback were seen at this time to be low-brow, with lurid, poor quality content. This perception continued until the printing of the first Penguin Books Paperback in 1935.

Modern books
Founded by Sir Allen Lane, the principle idea behind Penguin paperbacks was to print high-brow titles in large quantities for an available price. The revolutionary idea was a success, and a mere ten months after their creation Penguin had printed over 1m books.

There is a large collecting community for Modern First Editions, classics of 20th century literature. Due to the increasing availability of digital books, the value of these are largely based on the condition of the binding and illustrated dust jackets of each volume, as well as authors signatures and inscriptions.

The 21st century has seen the development of the e-book, a digital book which can be downloaded and read on computers, phones and dedicated devices known as e-readers. E-books represented 31.1% of all book sales in 2012.

It is often specific authors who attract the attention of bibliophiles. They have to narrow their interest down somehow, and many may have a nostalgic or intellectual interest in one literary figure.

Many collectors veer towards fiction. They focus on the authors that they love to read, those who paint the world in a light that is at once revealing and familiar. These authors are often famous historical literary figures, whose stories have been studied across centuries. From the escapism of C. S. Lewis, to the romanticism of Charlotte Bronte, the adventures of Robert Louis Stevenson, the dark world of Edgar Allen Poe, the mystery and suspense of Agatha Christie, and the politically stirring tracts of Graham Greene, fiction boasts endless favourites among collectors.

However, there is a whole world of non-fiction books that entice others. Some focus on antique medical books, travel and exploration, or early works of natural history. An exciting focus is books that changed the world, books that altered the course of history. Whether this means the Gutenberg Bible, or Charles Darwin’s On the Origin of Species, it is safe to say that collectors love a book with historical significance.

Others focus on modern literature. While this is more accessible, as it was generally mass produced, first editions in good condition can be extremely valuable – particularly if the work in question is considered a modern classic. For example, a first edition of F Scott Fitzgerald’s The Great Gatsby, written in the 1920s, achieved $163,500 in 2002. Ian Fleming’s original James Bond novels, replete with fantastic illustrated dust jackets, are extremely popular.

Some collectors focus heavily on nostalgia, and antique & vintage children’s books have a vast collecting community. The Victorian adventures of Alice in Wonderland by Lewis Carroll, with illustrations by John Tenniel, or A. A. Milne’s Winnie the Pooh books, or the classics of Beatrix Potter – all these, as well as numerous more obscure works, are snapped up by collectors interested in the charming history of books for children. More modern children's writers are also receiving increasing interest from collectors, such as Maurice Sendak and Dr Seuss.

Others may be drawn to writers because they were, at their time of publishing, extremely controversial – often banned. Many of these works, today considered classics, were too contentious or explicit for the era they were written in. Works such as John Steinbeck’s The Grapes of Wrath, banned for its exposure of the cruel treatment of migrant workers during the depression, is now considered a great American classic. Even the children’s adventure favourite, Mark Twain’s Adverntures of Huckleberry Finn was once thought of as too coarse. George Orwell’s criticism of Soviet corruption, Animal Farm, was banned during the Second World War as the U.S.S.R fought alongside the allies. All these and numerous others, once considered not fit for public regard, are now some of the most valuable books on the market."