PG has been operating since 1971; it moved into high gear in 2001, when Distributed Proofreaders began adding books. Both PG and DP are non-profit and volunteer-run. Their free books are put out as text files and HTML files; the HTML files are easily converted into other file formats. Hence you’ll find PG books everywhere, usually without acknowledgment of the original source.

Google Books is much wider in scope but the products are less useful. The OCR is uncorrected, which means that it’s full of scannos. The PDF files are huge and hard to read on hand-held devices. If you have bad eyesight, you can’t increase the font size without increasing the page size.

DP is harvesting Google page images, redoing and hand-correcting the OCR, and producing much more usable ebooks. But we’re a lot slower than Google …