The paperback of The Etymologicon is released today in Britain. I don't really know why it's a paperback and not a paperfront. In fact, like me, it's soft all round. In the USA they have, occasionally, paperbounds, which make a lot more sense.
Paperbacks were introduced in the 1840s to supply the newly literate lower classes with something on which to expend their literacy. They were sometimes called penny-dreadfuls (cost and quality) and sometimes called yellow-backs because they were printed in bright colours (often, as you may have guessed, yellow).
Paperback is first recorded in 1843, but hardback isn't recorded until 1954. Well, to be fair hardback was recorded in 1750 as the name of a kind of West Indian coleopterous insect, and in 1883 as the name of a central American fish. But hardback as a kind of book doesn't appear until over a century after paperback, despite the fact that hardbacks were there first.
This is a classic example of the retronym. Organic food, live music and acoustic guitars were all there first. However, the introduction of pesticides, records and electric guitars meant that you then had to start specifying. It's something I always consider when travelling on the London Overground.
Anyway, if you found your hardback Etymologicon too cruelly granite-like, or if you once had a bad experience with a coleopterous West Indian, you can now rush to the bookshop and ask for something softer.