From 2002-2004 an important innovation was developed, in support of
the creation of new Project Gutenberg eBooks. This was Distributed
Proofreaders, an early example of what is now known as crowdsourcing.
Through Distributed Proofreaders, volunteers engage in a portion of
the eBook creation process — whether it is copyright clearances,
proofreading (a page at a time!), or formatting, checking, and
finalization before uploading. Those portions, when coordinated
together, lead to the creation of new eBooks from printed sources.
Distributed Proofreaders has become the single largest source for new
eBooks to the collection, accounting for approximately half of all
titles. Distributed Proofreaders has also innovated substantially in
the use of HTML+CSS (cascading style sheets) for very attractive
presentation of eBooks in Web browsers.