Rather a nice concise description from Chapter 1 of Ruth Scurr’s John Aubrey: My own life (New York Review Books, 2016).

Looking back he [Aubrey] wrote:

‘Before Printing, Old-wives Tales were ingeniouse: and since Printing came into fashion, till a little before the Civil-warres, the ordinary sort of People were not taught to reade: now-a-dayes Books are common, and most of the poor people understand letters: and the many good Bookes and variety of Turnes of Affaires, have putt all the old Fables out of dores: and the divine art of Printing and Gunpowder have frightened away Robin-goodfellow and the Fayries.’

In Aubrey’s time, most books were sold in London, at booksellers’ shops or stalls clustered around St Paul’s churchyard. From here the book trade spread out to towns with printing presses: Oxford, Cambridge, York, Ipswich, Exeter, Edinburgh, Glasgow, Aberdeen, St Andrews. Chapmen or carriers transported books to dealers in the provinces. Distribution became easier after the introduction of the postal service in 1635. Paper in England was more expensive than in the rest of Europe because it had to be imported; there was no successful manufacture of white paper for printing in England until the eighteenth century. When it was sold, it was counted in quires (24 or 25 sheets) or reams (20 quires, so 480 or 500 sheets). Publication of books was funded by an undertaker, usually a bookseller, occasionally an author or printer. It was the financial backer who owned the copyright in this period. Stationers’ Hall, where an undertaker could register ownership of a book after having agreed to finance it, was close to St Paul’s. For the booming book trade, the Great Fire of London of 1666 — known as the Memorable, General or Great Conflagration in Aubrey’s time — was a catastrophe.

And later:

In London, I got lost among the piles of books for sale in St Paul’s churchyard; most of them are sold in sheets, but some are already bound. I pick up one after another without any idea where to begin: the books that are bound all look alike. How to tell which will be worth buying with my spare money? I come away empty handed, overwhelmed, as though the books have become trees again and I am wandering blind in a forest. Back in Dr Bathurst’s library, I can explore more calmly; I am starting to find my way.

Reprinted by kind permission of the publisher.