(1) "Light Literature", such as Alice's Adventures in Wonderland, Through the Looking-Glass, Peter Pan and Aesop's Fables; (2) "Heavy Literature", such as the Bible, Shakespeare's works, Moby Dick and Paradise Lost; (3) "Reference Literature", such as Roget's Thesaurus, almanacs, and a set of encyclopedias and dictionaries. A more detailed classification was released years later.

Project Gutenberg's goal has been more about selecting books intended for the general public than providing authoritative editions. As explained on the website in 1997: "We do not write for the reader who cares whether a certain phrase in Shakespeare has a ':' or a ';' between its clauses. We put our sights on a goal to release etexts that are 99.9% accurate in the eyes of the general reader."

1998 > A collection in Plain Vanilla ASCII

The etexts, later called ebooks, were stored in the simplest way, using the low set of ASCII, called Plain Vanilla ASCII, for them to be read on any hardware and software. As a text file, a book could be easily copied, indexed, searched, analyzed, and compared with other books. Pietro di Miceli was the sole driving force behind the Project Gutenberg's website for nearly a decade, after making the first pages in 1994.

August 1998 > "We consider etext to be a new medium."

As explained by Michael Hart in August 1998: "We consider etext to be a new medium, with no real relationship to paper, other than presenting the same material, but I don't see how paper can possibly compete once people each find their own comfortable way to etexts, especially in schools. (…) My own personal goal is to put 10,000 etexts on the Net [a goal reached in October 2003] and if I can get some major support, I would like to expand that to 1,000,000 and to also expand our potential audience for the average etext from 1.x% of the world population to over 10%, thus changing our goal from giving away 1,000,000,000,000 etexts to 1,000 times as many, a trillion and a quadrillion in U.S. terminology." (NEF Interview)

May 1999 > eBook #2000 > Don Quijote, by Cervantes

Project Gutenberg reached 2,000 ebooks in May 1999. eBook #2000 was Don Quijote (1605), by Cervantes, in Spanish, its original language.

October 2000 > Distributed Proofreaders

Distributed Proofreaders was founded in October 2000 by Charles Franks to share the proofreading of ebooks between many volunteers. Volunteers choose one of the digitized books available on the website and proofread a given page, or several pages, as they wish. It is recommended they do one page per day if possible. It may not seem much, but with thousands of volunteers it really adds up.

December 2000 > eBook #3000 > À l'ombre des jeunes filles en fleurs, by Marcel Proust

Project Gutenberg reached 3,000 ebooks in December 2000. EBook #3000 was À l'ombre des jeunes filles en fleurs (In the Shadow of Young Girls in Flower), vol. 3 (1919), by Marcel Proust, in French, its original language. From 1998 to 2000, there was an average of 36 new ebooks per month.

August 2001 > Project Gutenberg Australia

Project Gutenberg Australia was launched in August 2001. The collection included 500 ebooks in July 2005, and 1,500 ebooks in April 2007.

October 2001 > eBook #4000 > The French Immortals Series

Project Gutenberg reached 4,000 ebooks in October 2001. eBook #4000 was The French Immortals Series (1905), in English. This book is an anthology of short fictions by authors from the French Academy (Académie Française): Emile Souvestre, Pierre Loti, Hector Malot, Charles de Bernard, Alphonse Daudet, and others. In 2001, there was an average of 104 new ebooks per month.

April 2002 > eBook #5000 > The Notebooks of Leonardo da Vinci

Project Gutenberg reached 5,000 ebooks in April 2002. eBook #5000 was The Notebooks of Leonardo da Vinci, an English version of Leonardo's early 16th-century writings in Italian. Since its release, this ebook has constantly stayed in the Top 100 downloaded ebooks.

2002 > 1.44 M standard disks and zipped files

In 1991, Alice's Adventures in Wonderland and Peter Pan each fit on one 360 K disk, the standard of the time. In 2002, the standard disk was 1.44 M and could be compressed as a zipped file. A practical file size is about 3 million characters, more than long enough for the average book. The ASCII version of a 300-page novel is 1 M. A bulky book can fit in two ASCII files, that can be downloaded as is or zipped. 50 hours on average are necessary to get an ebook selected, copyright- cleared, scanned, proofread, formatted, and assembled.

Spring 2002 > 25% of all public domain works

In spring 2002, the Project Gutenberg collection represented 25% of all public domain works freely available on the web and listed in the Internet Public Library (IPL). In 2002, there was an average of 203 new ebooks per month.

November 2002 > The Human Genome Project

In November 2002, Project Gutenberg released the 75 files of The Human Genome Project, with files of dozens or hundreds of megabytes, shortly after its initial release in February 2001 as a work from public domain.

September 2003 > Project Gutenberg Audio eBooks

In September 2003, Project Gutenberg Audio eBooks was launched as a collection of human-read ebooks, and the Sheet Music Subproject as a collection of digitized music sheet and music recordings. A collection of still and moving pictures was also available.

October 2003 > eBook #10000 > The Magna Carta

1,000 ebooks in August 1997, 2,000 ebooks in May 1999, 3,000 ebooks in December 2000, 4,000 ebooks in October 2001, 5,000 ebooks in April 2002, 10,000 ebooks in October 2003. eBook #10000 was The Magna Carta, the first English constitutional text, signed in 1215.

October 2003 > The collection doubled in 18 months

From April 2002 to October 2003, in 18 months, the collection of ebooks doubled, going from eBook #5000 to eBook #10000, with an average of 348 new ebooks per month in 2003. The fast growth was the hard work of Distributed Proofreaders, now going at full speed to digitize books and share the proofreading of ebooks between many volunteers.

December 2003 > The first Project Gutenberg DVD

eBooks were also copied on CDs and DVDs. As blank CDs and DVDs cost next to nothing, Project Gutenberg began burning and sending a free CD or DVD to anyone asking for it. People were encouraged to make copies for a friend, a library or a school. Released in August 2003, the Best of Gutenberg CD contained 600 ebooks. The first Project Gutenberg DVD was released in December 2003, with the burning of most titles (9,400 ebooks).

2003 > The Project Gutenberg Consortia Center (PGCC)

The Project Gutenberg Consortia Center (PGCC) was affiliated with Project Gutenberg in 2003. Since 1997, PGCC had been gathering collections of existing ebooks, as a complement to Project Gutenberg working on producing ebooks. As explained by Michael Hart in January 2009: "The Project Gutenberg Consortia Center has over 75,000 ebooks rendered as PDF files (…). The difference? These files were prepared by other eLibraries, not Project Gutenberg, and are using our worldwide distribution network to be seen." (NEF Interview)

January 2004 > Project Gutenberg Europe

In Europe, Project Rastko, based in Belgrade, Serbia, launched Project Gutenberg Europe (PG Europe) in January 2004, as well as Distributed Proofreaders Europe (DP Europe), with a web interface in 12